Multi-tuner multi-buffer digital home communication terminal

ABSTRACT

A method for receiving media content of multiple display channels at a digital home communication terminal (DHCT), comprising receiving first media content corresponding to a first display channel at a first tuner of the DHCT, receiving second media content corresponding to a second display channel at a second tuner of the DHCT, and presenting to a user of the DHCT a plurality of options to receive third media content using one of the first and second tuners at a time overlapping at least in part with a time in which the first and second media content are received.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/143,123, filed May 10, 2002, which claims priority to U.S.provisional application having Ser. No. 60/290,315, filed May 11, 2001,both of which are entirely incorporated herein by reference.

This application is related to copending U.S. patent application Ser.No. 10/143,647, filed May 10, 2002, which is entirely incorporatedherein by reference.

TECHNICAL FIELD

The present invention is generally related to television systems, and,more particularly, is related to personal video recording.

BACKGROUND OF THE INVENTION

With recent advances in digital transmission technology, subscribertelevision systems are now capable of providing much more than thetraditional analog broadcast video. In implementing enhancedprogramming, the home communication terminal device (“HCT”), otherwiseknown as the set-top box, has become an important computing device foraccessing media content services (and media content within thoseservices) and navigating a user through a maze of available services. Inaddition to supporting traditional analog broadcast video functionality,digital HCTs (or “DHCTs”) now also support an increasing number oftwo-way digital services such as video-on-demand and personal videorecording.

Typically, a DHCT is connected to a cable or satellite, or generally, asubscriber television system, and includes hardware and softwarenecessary to provide the functionality of the digital television systemat the user's site. Some of the software executed by a DHCT may bedownloaded and/or updated via the subscriber television system. EachDHCT also typically includes a processor, communication components, andmemory, and is connected to a television or other display device, suchas a personal computer. While many conventional DHCTs are stand-alonedevices that are externally connected to a television, a DHCT and/or itsfunctionality may be integrated into a television or personal computeror even an audio device such as a programmable radio, as will beappreciated by those of ordinary skill in the art.

DHCTs are typically capable of providing users with a very large numberand variety of media content choices. As the number of available mediacontent choices increases, viewing conflicts arise whereby the user mustchoose between watching two or more media content instances (e.g.,discrete, individual instances of media content such as, for anon-limiting example, a particular television show or “program”episode), all of which the user would like to view. Further, because ofthe large number of viewing choices, the user may miss viewingopportunities. Buffering of media content instances in memory, or morerecently, in storage devices (e.g., hard disk drives, CD-ROM, etc.)coupled to the DHCT, has provided some relief from the conflict inviewing choices while providing personal video recording functionality.However, current buffering mechanisms for personal video recording makeinefficient use of tuner and buffer resources for a plurality of displaychannel changes using buffering mechanisms that operate undersingle-tuner constraints and/or assumptions. Therefore, there exists aneed to exploit multi-tuner functionality to make more efficient use ofDHCT resources.

Thus, a heretofore unaddressed need exists in the industry to addressthe aforementioned deficiencies and inadequacies.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the invention can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present invention. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1A is a block diagram of an example subscriber television system(STS), in accordance with one embodiment of the invention.

FIG. 1B is a block diagram of the transmission signals supported by theSTS of FIG. 1A, and input into the digital home communication terminal(DHCT) from the headend, in accordance with one embodiment of theinvention.

FIG. 2 is a block diagram of an example headend as depicted in FIG. 1Aand related equipment, in accordance with one embodiment of theinvention.

FIG. 3A is a block diagram of an example DHCT as depicted in FIG. 1A andrelated equipment, in accordance with one embodiment of the invention.

FIG. 3B is a block diagram of example memory for the example DHCTdepicted in FIG. 3A, in accordance with one embodiment of the invention.

FIG. 3C is a schematic diagram of an example hard disk and hard diskelements located within the storage device coupled to the DHCT depictedin FIG. 3A.

FIG. 3D is a schematic diagram of an example remote control device toprovide input to the DHCT illustrated in FIG. 3A, in accordance with oneembodiment of the invention.

FIG. 4 is a schematic diagram illustrating an example conflict scenarioin a two tuner, two buffer system that would require the establishmentof priorities for receiving and buffering media content from a pluralityof display channels, in accordance with one embodiment of the invention.

FIGS. 5-11 are timing diagrams that illustrate some example resourceinteractions included in tuning, buffering, and displaying media contentamong a variety of analog and digital signal flow path configurations,in accordance with several embodiments of the invention.

FIGS. 12A-12C are flow diagrams that illustrate an example resourcemanagement process for tuning, buffering, and displaying media contentfrom a plurality of display channels for the configurations illustratedin FIGS. 5-11, in accordance with one embodiment of the invention.

FIGS. 13-17 are flow diagrams that illustrate steps for prioritizingbetween tuner resources and buffer space based on a plurality ofdownload durations in order to address the example scenario of FIG. 4,in accordance with several embodiments of the invention.

FIG. 18 is a screen diagram of an example decision barker screen thatenables a user to make decisions between which downloaded displaychannel media content to displace in order to receive new media contentfrom a new display channel, in accordance with one embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the invention now will be described morefully hereinafter with reference to the accompanying drawings, in whichpreferred embodiments of the invention are shown. One way ofunderstanding the preferred embodiments of the invention includesviewing them within the context of a subscriber television system, andmore particularly within the context of a media client device, such as adigital home communication terminal (DHCT). The DHCT provides for userinteraction with what is displayed on a television and what is bufferedinto an associated storage device. Although other communicationenvironments are considered to be within the scope of the preferredembodiments, the preferred embodiments of the invention will bedescribed in the context of a DHCT that receives media content from aheadend over a subscriber network as one example implementation amongmany.

Because the preferred embodiments of the invention can be understood inthe context of a subscriber television system environment, an initialdescription of a subscriber television system is followed with adescription of the types of transmission signals that are included inthe subscriber television system, in addition to further description ofthe headend and DHCT (and coupled storage device) that are includedwithin the subscriber television system. The preferred embodiments ofthe invention include controlling rules for displaying and bufferingmedia content in a multi-tuner, multi-display channel changingenvironment. Thus, the description that follows the DHCT discussion willhelp to illustrate what resources are included in tuning, displayingand/or storing media content at the DHCT, and how those resources aremanaged and allocated to implement a plurality of display channelchanges.

Following the discussion on resource allocation and management is adescription of input variables, and how the input variables are used inthe context of a rule based system of the preferred embodiments toproduce a set of consequences and/or outputs to make decisions on whatmedia content to receive and buffer during a plurality of displaychannel changes.

This description of input variables in the context of a rule-basedsystem is followed by a description of some example implementations thatrely on the rule based system to provide for efficient functioning ofthe personal video recording (PVR) system of the DHCT

The preferred embodiments of the invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those having ordinary skill in theart. Furthermore, all “examples” given herein are intended to benon-limiting, and are provided as an exemplary list among many otherexamples contemplated but not shown.

One embodiment of the invention is generally implemented as part of asubscriber television system (STS), which includes digital broadbanddelivery systems (DBDS) and cable television systems (CTS). As anon-limiting example, a subscriber television system (STS) and itsoperation will be described initially, with the understanding that otherconventional data delivery systems are within the scope of the preferredembodiments of the invention. FIG. 1A shows a block diagram view of anSTS 10, which is generally a high quality, reliable and integratednetwork system that is typically capable of delivering video, audio,voice and data services to digital home communication terminals (DHCTs)16. Although FIG. 1A depicts a high level view of an STS 10, it shouldbe appreciated that a plurality of subscriber television systems can tietogether a plurality of regional networks into an integrated globalnetwork so that DHCT users can receive media content provided fromanywhere in the world. Further, it will be appreciated that the STS 10shown in FIG. 1A is merely illustrative and should not be construed asimplying any limitations upon the scope of the preferred embodiments ofthe invention. For instance, subscriber television systems also includedwithin the scope of the preferred embodiments of the invention includesystems not utilizing physical structured cabling for transmission, suchas, but not limited to, satellite systems. Further, transmission mediaincluded within the scope of the preferred embodiments of the inventioninclude, but are not limited to, Hybrid Fiber/Coax (HFC), optical,satellite, radio frequency (RF), frequency modulated (FM), andmicrowave. Further, data provided from the headend 11 to the DHCTs 16and programming necessary to perform the functions discussed below willbe understood to be present in the STS 10, in accordance with thedescription below.

The STS 10 typically delivers broadcast video signals as digitallyformatted signals in addition to delivering traditional broadcast analogvideo signals. Furthermore, the system can typically support one waybroadcast services as well as both one-way data services and two-waymedia content and data services. The two-way operation of the networktypically allows for user interactivity with services, such asPay-Per-View programming, Near Video-On-Demand (NVOD) programmingaccording to any of several known NVOD implementation methods,Video-on-Demand (VOD) programming (according to any of several VODimplementation methods), and interactive applications, such as Internetconnections.

The STS 10 also provides the interfaces, network control, transportcontrol, session control, and servers to access media content from mediacontent services, and distributes media content to DHCT users. As shownin FIG. 1A, a typical STS 10 comprises a headend 11, hubs 12, an HFCaccess network 17, nodes, 13, taps 14, and DHCTs 16. It should beappreciated that although a single component (e.g., a headend) isillustrated in FIG. 1A, an STS 10 can feature a plurality of any one ofthe illustrated components, can omit components, or may be configuredwith alternative embodiments for any one of the individual components orwith yet other additional components not enumerated above.

Media content provided by one or more content providers (not shown) iscommunicated by the content providers to one or more headends 11. Fromthose headends 11 the media content is then communicated over acommunications network 18 that includes a plurality of HFC accessnetworks 17 (only one HFC access network 17 is illustrated). The HFCaccess network 17 typically comprises a plurality of HFC nodes 13, eachof which may serve a local geographical area. The hub 12 connects to theHFC node 13 through a fiber portion of the HFC access network 17. TheHFC node 13 is connected to a tap 14 that is connected to a digital homecommunication terminal (DHCT) 16. Coaxial cables are typically used tocouple nodes 13 and taps 14 because the electrical signals can be easilyrepeated with RF amplifiers. As the high-level operations of many of thefunctions of an STS 10 are well known to those of ordinary skill in theart, further high level description of the overall STS 10 of FIG. 1Awill not be contained herein FIG. 1B is a block diagram illustrating thetransmission signals supported by the STS 10 (FIG. 1A), where thetransmission signals 60, 64, 68, and 72 are input into a DHCT 16 inaccordance with one embodiment of the invention. One or more contentproviders (not shown) are the source of the information that is includedin the transmission signals. Before passing through the network 17 (FIG.1), transmission signals can be generated at a headend 11 or at a hub 12(FIG. 1A) that might function as a mini-headend and which thereforepossesses some of the headend functionality.

As depicted in FIG. 1B, the STS 10 (FIG. 1A) can simultaneously supporta number of transmission signal types, transmission rates, andmodulation formats. The ability to carry analog and digital signals overa large bandwidth are characteristics of an HFC network typicallyemployed in an STS, as in the STS 10 of FIG. 1A. As will be appreciatedby those of ordinary skill in the art, analog and digital signals in HFCnetworks can be multiplexed using Frequency Division Multiplexing (FDM),which enables many different types of signals to be transmitted over theSTS 10 to the DHCT 16. Typically, an STS 10 using HFC supportsdownstream (i.e., in the direction from the headend 11 to the DHCT 16)frequencies from 50 mega-hertz (MHz) to 870 MHz, whereas upstreamfrequencies (i.e., in the direction from the DHCT 16 to higher levels ofthe system) are in the 5 MHz to 42 MHz band. Generally, the RF bandwidthspacing for analog and digital services is 6 MHz. Furthermore, for atypical 870 MHz system in the United States, a possible downstream RFspectrum subdivision plan uses 6 MHz frequency subdivisions, or spans,within the 50 MHz to 550 MHz band for analog video transmission signalsand within the 550 MHz to 870 MHz range for digital transmissionsignals.

Analog Transmission Signals (ATSs) 60 shown in FIG. 1B are typicallybroadcast in 6 MHz frequency subdivisions, typically referred to inanalog broadcasting as channels, having an analog broadcast signalcomposed of analog video and analog audio, and include Broadcast TVSystems Committee (BTSC) stereo and Secondary Audio Program (SAP) audio.Referring again to FIG. 1B, the downstream direction transmissionsignals, having been multiplexed, and in one embodiment using FDM, areoften referred to as in-band transmission signals and include the ATSs60 and Digital Transmission Signals (DTSs) 64, 68, 72 (also known asDigital Transport Signals). These transmission signals carry video,audio, and/or data services. For example, these transmission signals maycarry television signals, Internet data, and/or any additional types ofdata, such as Interactive Program Guide (IPG) data. Additionally, aswill be appreciated by those of ordinary skill in the art, additionaldata can be sent with the analog video image in the Vertical BlankingInterval (VBI) of the video signal and stored in DHCT memory or a DHCTlocal physical storage device (not shown). It should be appreciated,however, that the amount of data that can be transmitted in the VBI ofthe analog video signal is typically significantly less than datatransmitted in a DTS.

Like the ATSs 60, the DTSs 64, 68, 72 each typically occupies 6 MHz ofthe RF spectrum. However, the DTSs 64, 68, and 72 are digitaltransmission signals consisting of 64- or 256-Quadrature AmplitudeModulated (QAM) digital signals formatted preferably using MovingPicture Experts Group (MPEG) standards such as MPEG-2 transport streams,allocated in a separate frequency range. The MPEG-2 transport streamenables transmission of a plurality of DTS types over each 6 MHz RFsubdivision, as compared to a 6 MHz ATS. The three types of digitaltransport signals illustrated in FIG. 1B include broadcast digitaltransmission signals 64, carousel digital transmission signals 68, andon-demand transmission signals 72.

MPEG-2 transport may be used to multiplex video, audio, and data in eachof these Digital Transmission Signals (DTSs). However, because an MPEG-2transport stream allows for multiplexed video, audio, and data into thesame stream, the DTSs do not necessarily have to be allocated inseparate 6 MHz RF frequencies, unlike the ATSs 60 in one embodiment. Onthe other hand, each DTS is capable of carrying multiple broadcastdigital media content instances, multiple cycling data carouselscontaining broadcast data, and data requested on-demand by thesubscriber. Data is formatted, such as in Internet Protocol (IP), mappedinto MPEG-2 packets, and inserted into the multiplexed MPEG-2 transportstream. Encryption can be applied to the data stream for security sothat the data may be received only by authorized DHCTs. The authorizedDHCT 16 is provided with the mechanisms to receive, among other things,additional data or enhanced services. Such mechanisms can include “keys”that are required to decrypt encrypted data.

Each 6 MHz RF subdivision assigned to a digital transmission signal cancarry the video and audio streams of the media content instances ofmultiple television (TV) stations, as well as media content and datathat is not necessarily related to those TV media content instances, ascompared to one TV channel broadcast over one ATS 60 that consumes theentire 6 MHz. The digital data is inserted into MPEG transport streamscarried through each 6 MHz frequency subdivision assigned for digitaltransmission, and then demultiplexed at the subscriber DHCT so thatmultiple sets of data can be produced within each tuned 6 MHz frequencyspan, or subdivision.

Although broadcast in nature, the carousel DTSs 68 and on-demand DTSs 72offer different functionality. Continuing with FIG. 1B, the broadcastDTSs 64 and carousel DTSs 68 typically function as continuous feed foran indefinite time, whereas the on-demand DTSs 72 are continuous feedssessions for a limited time. In one embodiment, all DTS types arecapable of being transmitted at high data rates. The broadcast DTSs 64preferably carry data comprising multiple digitally-MPEG-2 compressedand formatted TV source signals and other continuously fed datainformation. The carousel DTSs 68 carry broadcast media content or datathat is systematically broadcast in a cycling fashion but updated andrevised as needed. Thus, the carousel DTSs 68 serve to carry high volumedata such as media content and data and possibly, other data at highdata rates.

The carousel DTSs 68 preferably carry data formatted in directories andfiles by a Broadcast File System (BFS) (not shown), which is used forproducing and transmitting data streams throughout the STS 10, and whichprovides an efficient means for the delivery of application executablesand application media content and data to the DHCT, as will be describedbelow. Media content and data received by the DHCT 16 in such manner canthen be saved in the DHCT memory and/or transferred to the DHCT storagedevice for later use. The on-demand DTSs 72, on the other hand, cancarry particular information such as compressed video and audiopertaining to subscriber requested media content instance preview and/ormedia content instance descriptions, as well as other specialized datainformation.

Preferably, the User-to-Network Download Protocol of the MPEG-2standard's DSM-CC specification (Digital Storage Media-Command andControl) preferably provides the data carousel protocol used forbroadcasting data from a server located at the headend 11, or locatedelsewhere. It also provides the interactive download protocol forreliable downloading of data from a server (possibly the same server) toan individual DHCT through the on-demand DTSs. Each carousel andon-demand DTS is preferably defined by a DSM-CC session. Therefore, someof the basic functionality reflected in the DHCT 16 when the DHCT doesnot have a local physical storage device is somewhat similar to anetworked computer (i.e., a computer without a persistent storagedevice), in addition to traditional set top box functionality, as iswell known to those of ordinary skill in the art. A DHCT 16 with astorage device reduces data access latency when the data is stored inthe local physical storage device ahead of time.

Also shown in FIG. 1B are Out-Of-Band (OOB) signals that providecontinuously available two-way signaling to the subscribers' DHCT 16regardless of which in-band signals are tuned to by the individual DHCTin-band tuners. The OOB signals consist of a Forward Data Signal (FDS)76 and a Reverse Data Signal (RDS) 80. The OOB signals can comply to anyone of a number of well known transport protocols but preferably complyto either a Digital Audio Visual Council (DAVIC) 1.1 Transport Protocolwith an FDS of 1.544 mega-bits per second (Mbps) or more usingquadrature phase shift keying (QPSK) modulation and an RDS of 1.544 Mbpsor more using QPSK modulation, or to a Data Over Cable Service InterfaceSpecification (DOCSIS) Transport Protocol with an FDS of 27 Mbps using64-QAM modulation and an RDS of 1.544 Mbps or more using QPSK modulationor 16-QAM modulation. The OOB signals provide the two-way operation ofthe network, which allows for subscriber interactivity with theapplications and services provided by the network. Furthermore, the OOBsignals are not limited to a 6 MHz spectrum, but generally to a smallerspectrum, such as 1.5 or 3 MHz.

FIG. 2 is an overview of one example headend 11, which provides theinterface between the STS 10 (FIG. 1A) and the service and contentproviders. The overview of FIG. 2 is equally applicable to one examplehub 12 (FIG. 1A), and the same elements and principles may beimplemented at the hub 12 instead of the headend 11 as described herein.It will be understood that the headend 11 shown in FIG. 2 is merelyillustrative and should not be construed as implying any limitationsupon the scope of the preferred embodiments of the invention. Theheadend 11 receives content from a variety of service and contentproviders, which can provide input in a variety of ways. The headend 11combines the content from the various sources and distributes thecontent to subscribers via the distribution systems of the network 18.

In a typical system, the programming, services and other informationfrom content providers can be distributed according to a variety ofmechanisms. The input signals may be transmitted from sources to theheadend 11 via a variety of transmission paths, including satellites(not shown), and terrestrial broadcast transmitters and antennas (notshown). The headend 11 can also receive content from a direct feedsource 210 via a direct line 212. Other input sources from contentproviders include a video camera 214, an analog input source 208, or anapplication server 216. The application server 216 may include more thanone line of communication. One or more components such as the analoginput source 208, the input source 210, the video camera 214, and theapplication server 216 can be located external to the headend 11, asshown, or internal to the headend 11 as would be appreciated by onehaving ordinary skill in the art. The signals provided by the content orprogramming input sources can include a single media content instance ora multiplex that includes several media content instances.

The headend 11 generally includes one or more receivers 218 that areeach associated with a content source. In one implementation, MPEGencoders, such as encoder 220, are included for digitally encoding localprogramming or a real-time feed from the video camera 214, or the like.In other implementations, an encoder can be located externally to theheadend 11. The encoder 220 outputs the respective compressed video andaudio streams corresponding to the analog audio/video signal received atits input. For example, the encoder 220 can output formatted MPEG-2 orMPEG-1 packetized elementary (PES) streams or transport streamscompliant to the syntax and semantics of the ISO MPEG-2 standard,respectively. The PES or transport streams may be multiplexed with inputsignals from a switch 230, the receiver 218 and a control system 232.The multiplexing logic 222 processes the input signals and multiplexesat least a portion of the input signals into a transport stream 240. Theanalog input source 208 can provide an analog audio/video broadcastsignal which can be input into a modulator 227. From the modulator 227,a modulated analog output signal can be combined at a combiner 246 alongwith other modulated signals for transmission into a transmission medium250. Alternatively, an analog audio/video broadcast signal from theanalog input source 208 can be input into the modulator 228.Alternatively, an analog audio/video broadcast signal can be inputdirectly from the modulator 227 to the transmission medium 250. Theanalog broadcast media content instances are transmitted via respectiveRF channels, each assigned for transmission of an analog audio/videosignal such as National Television Standards Committee (NTSC) video, asdescribed in association with FIG. 1B.

The switch, such as an asynchronous transfer mode (ATM) switch 230,provides an interface to an application server 216. There can bemultiple application servers 216 providing a variety of services such asa Pay-Per-View service, including video on demand (VOD), a data service,an Internet service, a network system, or a telephone system. Serviceand content providers may download content to an application serverlocated within the STS 10. The application server 216 may be locatedwithin the headend 11 or elsewhere within the STS 10, such as in a hub12. The various inputs into the headend 11 are then combined with theother information from the control system 232, which is specific to theSTS 10, such as local programming and control information, which caninclude, among other things, conditional access information.

The headend 11 contains one or more modulators 228 to convert thereceived transport streams 240 into modulated output signals suitablefor transmission over the transmission medium 250 through the network18. Each modulator 228 may be a multimodulator including a plurality ofmodulators, such as, but not limited to, QAM modulators, that radiofrequency modulate at least a portion of the transport streams 240 tobecome output transport streams 242. The output signals 242 from thevarious modulators 228 or multimodulators are combined, using equipmentsuch as the combiner 246, for input into the transmission medium 250,which is sent via the in-band delivery path 254 to subscriber locations(not shown). The in-band delivery path 254 can include DTS 64, 68, 72,and ATS 60, as described with FIG. 1B.

In one embodiment, the server 216 also provides various types of data288 to the headend 11. The data, in part, is received by media accesscontrol functions 224 that output MPEG transport packets containing data266 instead of digital audio/video MPEG streams. The control system 232enables the television system operator to control and monitor thefunctions and performance of the STS 10. The control system 232interfaces with various components, via communication link 270, in orderto monitor and/or control a variety of functions, including thefrequency spectrum lineup of the programming for the STS 10, billing foreach subscriber, and conditional access for the content distributed tosubscribers. Information, such as conditional access information, iscommunicated from the control system 232 to the multiplexing logic 222where it is multiplexed into the transport stream 240.

Among other things, the control system 232 provides input to themodulator 228 for setting the operating parameters, such as selectingcertain media content instances or portions of transport streams forinclusion in one or more output transport stream 242, system specificMPEG table packet organization, and/or conditional access information.Control information and other data can be communicated to hubs 12 (FIG.1A) and DHCTs 16 (FIG. 1A) via an in-band delivery path 254 or via anout-of-band delivery path 256.

The out-of-band data is transmitted via the out-of-band FDS 76 of thetransmission medium 250 by, but not limited to, a Quadrature Phase-ShiftKeying (QPSK) modem array 226. Two-way communication utilizes the RDS 80of the out-of-band delivery path 256. Hubs 12 (FIG. 1A) and DHCTs 16(FIG. 1A) transmit out-of-band data through the transmission medium 250,and the out-of-band data is received in the headend 11 via theout-of-band RDS 80. The out-of-band data is routed through router 264 tothe application server 216 and/or to the control system 232. Theout-of-band control information includes such information as, amongothers, a pay-per-view purchase instruction and a pause viewing commandfrom the subscriber location to a video-on-demand type applicationserver located internally or external to the headend 11, such as theapplication server 216, as well as any other data sent from the DHCT 16or hubs 12, all of which will preferably be properly timed. The controlsystem 232 also monitors, controls, and coordinates all communicationsin the subscriber television system, including video, audio, and data.The control system 232 can be located at the headend 11 or remotely.

The transmission medium 250 distributes signals from the headend 11 tothe other elements in the subscriber television system, such as the hub12, the node 13, and subscriber locations (FIG. 1A). The transmissionmedium 250 can incorporate one or more of a variety of media, such asoptical fiber, coaxial cable, HFC, satellite, direct broadcast, or othertransmission media.

FIG. 3A is a block diagram illustration of an example DHCT 16 that iscoupled to the headend 11 and to a television 341, in accordance withone embodiment of the invention. It will be understood that the DHCT 16shown in FIG. 3A is merely illustrative and should not be construed asimplying any limitations upon the scope of the preferred embodiments ofthe invention. For example, some of the functionality performed byapplications executed in the DHCT 16 (such as an MOD application 363(FIG. 3B)) may instead be performed completely or in part at the headend11 and vice versa, or not at all in some embodiments. A DHCT 16 istypically situated at the residence or place of business of a user andmay be a stand-alone unit or integrated into another device such as, forexample, a television set or a personal computer or other displaydevices or an audio device. The DHCT 16 preferably includes acommunications interface 342 for receiving signals (video, audio and/orother data) from the headend 11 through the network 18 and for providingany reverse information to the headend 11 through the network 18.

The DHCT 16 further preferably includes one or more processors, such asprocessor 344, for controlling operations of the DHCT 16, and a tunersystem 345, which preferably comprises two tuners, tuner1 354 and tuner2358, for tuning into a particular television channel or frequency todisplay media content and for sending and receiving various types ofdata or media content to and from the headend 11. The DHCT 16 mayinclude, in other embodiments, more than two tuners for receivingdownloaded (or transmitted) media content. The tuner system 345 canselect from a plurality of transmission signals (FIG. 1B) provided bythe subscriber television system. The tuner system 345 enables the DHCT16 to tune to downstream media and data transmissions, thereby allowinga user to receive digital and/or analog media content delivered in thedownstream transmission via the subscriber television system. The tunersystem 345 includes, in one implementation, an out-of-band tuner forbi-directional QPSK data communication and two QAM tuners (in band)(tuner1 354 and tuner2 358) for receiving television signals. The tuners354 and 358 of tuner system 345 can be used to simultaneously receive aplurality of signals at different carrier frequencies, and/or atdifferent program identification (PID) locations to receive differentservices (e.g., receiving HBO and CNN on one carrier frequency, butdifferent PID locations) in an MPEG formatted signal. Additionally, areceiver 346 receives externally generated information, such as userinputs or commands from an input device, such as a remote control device380, or other devices.

According to another embodiment of the invention, a telephone modem (notshown) in the DHCT 16 can be utilized for upstream data transmission andthe headend 11, the hub 12 (FIG. 1A), or other components locatedupstream in the STS 10 (FIG. 1A) can receive data from a telephonenetwork corresponding with the telephone modem and can route theupstream data to a destination internal or external to the STS 10, suchas an application data server in the headend 11 or content provider.

The DHCT 16 includes a signal processing system 314, which comprisesdemodulating system 313 and transport demultiplexing and parsing system315 (herein demultiplexing system) to process broadcast media contentand/or data. One or more of the systems of the signal processing system314 can be implemented with software, a combination of software andhardware, or preferably in hardware. The demodulating system 313comprises functionality for RF signal demodulation, either an analogtransmission signal or a digital transmission signal. For instance, thedemodulating system 313 can demodulate a digital transmission signal ina carrier frequency that was modulated, among others, as a QAM-modulatedsignal.

When tuned to a carrier frequency corresponding to an analog TV signaltransmission, the demultiplexing system 315 is bypassed and thedemodulated analog TV signal that is output by the demodulating system313 is instead routed to an analog video decoder 316. The analog videodecoder 316 converts the analog video signal (i.e., the video portion ofa media content instance that comprises a video portion and an audioportion, such as NTSC video) received at its input into a respectivenon-compressed digital representation comprising a sequence of digitizedpictures and their respective digitized audio. In one implementation,the video consists of a sequence of fields spaced apart at approximatelyone-sixtieth of a second. A pair of consecutive fields constitutes apicture. The odd field contains the odd-numbered lines of the pictureand the even field contains the even-numbered lines of the picture. Theanalog video decoder 316 outputs the corresponding sequence of digitizedpictures and respective digitized audio. Each picture is a twodimensional entity of picture elements and each picture element containsa respective set of values. A picture element value comprises luminanceand chrominance information that are representative of brightness andcolor information at the spatial location of the picture element withinthe picture.

Digitized pictures and respective audio output by the analog videodecoder 316 are presented at the input of a compression engine 317.Digitized pictures and respective audio output by the analog videodecoder 316 can also be presented to a bypass 308, which acts through aninterface (not shown) such as ITU-656 (International TelecommunicationsUnion or ITU), and is dedicated for non-compressed digitized analogvideo and audio, for display on the TV 341. The compression engine 317is coupled to memory 349 and additionally to a local dedicated memory309 that is preferably DRAM, for input and processing of the inputdigitized pictures and the respective digitized audio. Alternatively,the compression engine 317 can have its own integrated memory (notshown). The compression engine 317 processes the sequence of digitizedpictures and digitized audio and converts them into a video compressedstream and an audio compressed stream, respectively. The compressedaudio and video streams are produced in accordance with the syntax andsemantics of a designated audio and video coding method, such asspecified by the MPEG-2 audio and MPEG-2 video ISO (InternationalOrganization for Standardization or ISO) standard, so that they can beinterpreted by a video decoder 323 (also known as a video decompressionengine) and an audio decoder 325 (also known as an audio decompressionengine) for decompression and reconstruction at a future time. Eachcompressed stream includes a sequence of data packets containing aheader and a payload. Each header includes a unique programidentification, or PID, associated with the respective compressedstream.

The compression engine 317 multiplexes the audio and video compressedstreams into a transport stream, such as an MPEG-2 transport stream, foroutput. Furthermore, the compression engine 317 can compress audio andvideo corresponding to more than one media content instance in parallel(e.g., from two tuned analog TV signals when the DHCT 16 possessesmultiple tuners) and to multiplex the respective audio and videocompressed streams into a single transport stream. The output ofcompressed streams and/or transport streams produced by the compressionengine 317 is preferably input to the signal processing system 314.Parsing capabilities within the signal processing system 314 allow forinterpretation of sequence and picture headers, for instance, annotatingtheir locations within their respective compressed stream for futureretrieval from a storage device 373. A compressed analog media contentinstance (e.g., TV program episode or show) corresponding to a tunedanalog transmission channel can be output as a transport stream by thesignal processing system 314 and presented as input for storage in thestorage device 373 via an interface 375 as will be described below. Thepacketized compressed streams can be also output by the signalprocessing system 314 and presented as input to the media engine 322 fordecompression by the video decompression engine 323 and the audiodecompression engine 325 for its display on the TV 341, as will bedescribed below.

The demultiplexing system 315 can include MPEG-2 transportdemultiplexing. When tuned to carrier frequencies carrying a digitaltransmission signal, the demultiplexing system 315 enables theseparation of packets of data, corresponding to the compressed streamsof information belonging to the desired media content instances, forfurther processing. Concurrently, the demultiplexing system 315precludes packets in the multiplexed transport stream that areirrelevant or not desired, such as packets of data corresponding tocompressed streams of media content instances of other media contentsignal sources (e.g., other TV channels), from further processing.

The parsing capabilities of the demultiplexing system 315 includesreading and interpreting the received transport stream withoutdisturbing its content, such as to interpret sequence and pictureheaders, for instance, to annotate their locations and correspondingtime offset within their respective compressed stream for futureretrieval from the storage device 373. Thus, the components of thesignal processing system 314 are capable of QAM demodulation, forwarderror correction, and demultiplexing MPEG-2 transport streams, andparsing elementary streams and packetized elementary streams, amongother functions. A compressed media content instance corresponding to atuned carrier frequency carrying a digital transmission signal can beoutput as a transport stream by the signal processing system 314 andpresented as input for storage in the storage device 373 via theinterface 375 as will be described below. The packetized compressedstreams can be also output by the signal processing system 314 andpresented as input to the media engine 322 for decompression by thevideo decompression engine 323 and the audio decompression engine 325,and output to an output stage 348, as will be described below.

One having ordinary skill in the art will appreciate that the signalprocessing system 314 will preferably include other components notshown, including memory, decryptors, samplers, digitizers (e.g.,analog-to-digital converters), and multiplexers. Further, otherembodiments will be understood, by those having ordinary skill in theart, to be within the scope of the preferred embodiments of the presentinvention, including analog signals (e.g., NTSC) that bypass one or moreelements of the signal processing system 314 and are forwarded directlyto the output stage 348. Further, outputs presented at correspondingnext-stage inputs for the aforementioned signal processing flow may beconnected via accessible memory 349 in which the outputting devicestores the output data and the inputting device thereafter inputs theoutput data written to memory 349 by the respective outputting device.Outputting and inputting devices include the analog video decoder 316,the compression engine 317, the media engine 322, the signal processingsystem 314, and components or subcomponents thereof. Further, it will beunderstood by those having ordinary skill in the art that components ofthe signal processing system 314 can be spatially located in differentareas of the DHCT 16. Further, it will be understood by those havingordinary skill in the art that, although the components of the signalprocessing system 314 are illustrated as being in communication with anincoming signal from the communications interface 342, the signal maynot necessarily be in the order shown for all signals.

The DHCT 16 also includes the media engine 322, which includes thedigital video decoder 323 (or video decompression engine), the digitalaudio decoder 325 (or audio decompression engine), the output stage 348,and the bypass 308, and other digital signal processing components notshown, as would be appreciated by those having ordinary skill in theart. For example, the demultiplexing system 315 is in communication withthe tuner system 345 and processor 344 to effect reception of digitalcompressed video streams, digital compressed audio streams, and datastreams corresponding to one or more media content instances to beseparated from other media content instances and/or streams transportedin the tuned transmission channel and to be stored in a first part (notshown) of DRAM 352 of DHCT 16 assigned to receive packets of one or moremedia content instances. Other dedicated memory may also be used formedia content instance packets.

Furthermore, while conducting this process, the demultiplexing system315 demultiplexes and separates desired compressed streams from thereceived transport stream without disturbing its content. Further, thedemultiplexing system 315 parses (i.e., reads and interprets) compressedstreams such as to interpret sequence headers and picture headers, anddeposits a transport stream carrying compressed streams of a mediacontent instance into DRAM 352. The processor 344 causes the transportstream in DRAM 352 to be transferred to the storage device 373 via theinterface 375. Under program control by the processor 344, thedemultiplexing system 315, in communication with the digital videodecoder 323, the storage device 373, and the processor 344, effectsnotification and/or transfer of received packets of one or morecompressed streams corresponding to one or more media content instancesfrom a first part of DRAM 352 to a second part (not shown) of DRAM 352assigned to the digital video decoder 323 and the digital audio decoder325. In other embodiments, the media engine 322 can have access to adedicated localized DRAM, such as A/V decoder memory 306 to facilitatesuch transfers. Upon demultiplexing and parsing the transport streamcarrying one or more media content instances, and in communication withthe processor 344, the signal processing system 314 outputs to DRAM 352ancillary data in the form of a table or data structure (not shown)comprising the relative or absolute location of the beginning of certainpictures in the compressed media content instance for convenience inretrieval during future operations.

In another embodiment, according to a plurality of tuners, andrespective number of demodulating systems 313, demultiplexing systems315, and signal processing systems 314, a respective number of broadcastdigital media content instances are received and routed to the hard disk300 of the storage device 373 simultaneously while performing thenecessary data annotations for each of the respective compressed mediastreams for their future retrieval from storage device 373.Alternatively, a single demodulating system 313, a single demultiplexingsystem 315, and a single signal processing system 314, each withsufficient processing capabilities can serve to process more than onedigital media content instance. One or more of the received broadcastdigital media content instances routed to the storage device 373 can berouted simultaneously to the media engine 322 for decoding and displayto the TV 341.

In another embodiment according to the aforementioned description, afirst tuner, for example tuner1 354 of tuning system 345 receives ananalog video signal corresponding to a first media content instance anda second tuner, for example tuner2 358 receives a digital compressedstream corresponding to a second media content instance. The first mediacontent instance is processed as an analog signal and the second mediacontent instance is processed as a digital compressed stream asdescribed above. The compressed digital version of the analog videosignal or the second media instance, or both, can be routed to thestorage device 373 while simultaneously performing the respective dataannotations required for future retrieval. Additionally, either or bothof the media instances can be routed simultaneously to the media engine322 for decoding and display on the TV 341.

In one implementation, the compression engine 317 can output formattedMPEG-2 or MPEG-1 packetized elementary streams (PES) inside a transportstream, all compliant to the syntax and semantics of the ISO MPEG-2standard. Alternatively, the compression engine 317 can output otherdigital formats that are compliant to other standards. The digitalcompressed streams output by the compression engine 317 corresponding toa media content instance are preferably deposited in local memory 309for the compression engine 317 and routed to the demultiplexing system315. The demultiplexing system 315 parses (i.e., reads and interprets)the transport stream generated by the compression engine 317 withoutdisturbing its content, such as to interpret picture headers, anddeposits the transport stream into DRAM 352. The processor 344 causesthe transport stream in DRAM 352 to be transferred to the storage device373. While parsing the transport stream, the demultiplexing system 315outputs to DRAM 352 ancillary data in the form of a table or datastructure (not shown) comprising the relative or absolute location ofthe beginning of certain pictures in the compressed media content streamfor the media content instance for convenience in retrieval duringfuture operations. In this way, random access operations such as fastforward, rewind, and jumping to a location in the compressed mediacontent instance can be attained.

In another embodiment, according to a plurality of tuners, respectivenumber of analog video decoders 316, and respective number ofcompression engines 317, the aforementioned compression of analog videoand audio is performed and routed to the hard disk 300 of the storagedevice 373 simultaneously on a respective number of analog media contentinstances. Alternatively, a single compression engine with sufficientprocessing capabilities can serve to compress more than one analog mediacontent instance.

The media engine 322 also includes the output stage 348. In oneimplementation, the output stage 348 can include a digital encoder(DENC) (not shown) for driving the TV display. In parallel to feeding aDENC, the output stage 348 can also route the video/audio signal foroutput in multiple formats. Such formats can include analog componentYPbPr, which can be used in High Definition Television (HDTV), somestandard televisions, and digital video disk (DVD) players. Anotherformat can be RGB component for personal computer displays. Anotherformat can include a digital version of an analog component, which isused with fiber optic cable connections. The DENC output can feeddigital analog converters (DAC—not shown) for output as composite video(CVBS), also known as baseband (e.g., V-output connection in a VCR orDVD player). In other implementations, the luma and chroma signals canbe kept separate to output “separate video” through DACs (e.g., S-videoconnection in a VCR or DVD player). The DENC output of the output stage348 can also feed an RF channel 3 and 4 modulator (not shown) that feedsa DAC. In another implementation, the output stage 348 outputs inparallel through an ITU-656 output port, either for internal routing ofthe video or to drive an external DENC (e.g., for VCR recording). Inother embodiments, the DENC can be external to the output stage 348. Inother embodiments, a DENC internal to the output stage 348 can be usedto drive an external DENC (not shown), and the external DENC can be usedto drive a Channel 3 and/or 4 RF modulator.

The DHCT 16 also includes a media memory 305. These components caninclude software and/or hardware to compose and store graphicalinformation created by the processor 344. These components enable thecompositing of graphical data with video into a picture for a TV displayas provided by capabilities in the media engine 322.

In one implementation, compressed video and audio streams receivedthrough an in-band tuner of the tuner system 345 or read from the localstorage device 373 is deposited continuously into a compressed audio andvideo section 306 of the media memory 305. Thereafter, one or more videodecompression engines 323 within the media engine 322 decompresscompressed MPEG-2 Main Profile/Main Level video streams read into thevideo decompression engine 323 from the compressed video buffer 306 ofthe media memory 305. Each picture decompressed by the videodecompression engine 323 is written to a reconstruction portion 307 ofthe media memory 305, where the reconstructed pictures are retained.

Alternatively, the pictures may be decompressed in the videodecompression engine 323, then scaled down as they are beingreconstructed in a procedural fashion by feeding data of thereconstructed pictures in raster-scan order from the video decompressionengine 323 to a video scaling unit (not shown). According to thisalternative, the scaled down reconstructed picture can be stored in oneof multiple scaled video picture buffers (not shown) in media memory 305in raster-scan order as they are reconstructed, such that a respectivescaled video picture buffer is dedicated to the motion video picture ofa program or video object (read from the local storage device 373) andincluded in the displayed presentation.

Additionally, one or more digital audio decompression engines 325 in themedia engine 322 can decode the compressed digital audio streamsassociated with the compressed digital video or read as an audio objectfrom the local storage device 373 in a similar fashion, allocatingrespective buffers as necessary. It should be appreciated that in someimplementations only one audio buffer may be required. Note that, insome embodiments, system memory 349 and media memory 305 can be unifiedas one physical memory device. It should be appreciated that the mediamemory 305 is a memory of finite number of bytes, and it serves as arepository for different data components. Compressed MPEG-2 videostreams are deposited in A/V decoder memory 306 allocated for compressedvideo and compressed audio, as described above. Decompressed audio isfed into an audio port (not shown) for playback. Further information onthe media memory and subcomponents thereof, in addition to other DHCTcomponents can be found in the patent application entitled, DIGITALSUBSCRIBER TELEVISION NETWORKS WITH LOCAL PHYSICAL STORAGE DEVICES ANDVIRTUAL STORAGE, filed on Jul. 30, 2001, assigned a Ser. No. 09/918,376,assigned to Scientific Atlanta, Inc., and herein incorporated byreference.

One or more programmed software applications, herein referred to asapplications, are executed by utilizing the computing resources in theDHCT 16. Note that an application typically includes a client part and aserver counterpart that cooperate to provide the complete functionalityof the application. FIG. 3B is a block diagram of an example systemmemory 349. The applications may be resident in FLASH memory 351 ordownloaded (or uploaded) into DRAM 352. Applications stored in FLASHmemory 351 or DRAM 352 are executed by the processor 344 (e.g., acentral processing unit or digital signal processor) under the auspicesof the operating system 353. Data required as input by an application isstored in DRAM 352 or FLASH memory 351 and read by the processor 344 asneed be during the course of application execution. Input data may bedata stored in DRAM 352 by a secondary application or other source,either internal or external to the DHCT 16, or possibly anticipated bythe application and thus created with the application at the time it wasgenerated as a software application, in which case it is stored in FLASHmemory 351. Data generated by an application is stored in DRAM 352 bythe processor 344 during the course of application execution. DRAM 352also includes application memory 370 that various applications may usefor storing and/or retrieving data.

An application referred to as a navigator 355 is also resident in FLASHmemory 351 for providing a navigation framework for services provided bythe DHCT 16. The navigator 355 registers for and in some cases reservescertain user inputs related to navigational keys such as channelincrement/decrement, last channel, favorite channel, etc. The navigator355 also provides users with television related menu options thatcorrespond to DHCT functions such as, for example, blocking a displaychannel or a group of display channels from being displayed in a displaychannel menu presented on a screen display.

The FLASH memory 351 also contains a platform library 356. The platformlibrary 356 is a collection of utilities useful to applications, such asa timer manager, a compression manager, a configuration manager, a hypertext markup language (HTML) parser, a database manager, a widgettoolkit, a string manager, and other utilities (not shown). Theseutilities are accessed by applications via application programminginterfaces (APIs) as necessary so that each application does not have tocontain these utilities. Two components of the platform library 356 thatare shown in FIG. 3B are a window manager 359 and a service applicationmanager (SAM) client 357.

The window manager 359 provides a mechanism for implementing the sharingof the screen regions and user input. The window manager 359 on the DHCT16 is responsible for, as directed by one or more applications,implementing the creation, display, and de-allocation of the limitedDHCT 16 screen resources. It allows multiple applications to share thescreen by assigning ownership of screen regions, or windows. The windowmanager 359 also maintains, among other things, a user input registry350 in DRAM 352 so that when a user enters a key or a command via theremote control device 380 or another input device such as a keyboard ormouse, the user input registry 350 is accessed to determine which ofvarious applications running on the DHCT 16 should receive datacorresponding to the input key and in which order. As an application isexecuted, it registers a request to receive certain user input keys orcommands. When the user presses a key corresponding to one of thecommands on the remote control device 380, the command is received bythe receiver 346 and relayed to the processor 344. The processor 344dispatches the event to the operating system 353 where it is forwardedto the window manager 359 which ultimately accesses the user inputregistry 350 and routes data corresponding to the incoming command tothe appropriate application.

The SAM client 357 is a client component of a client-server pair ofcomponents, with the server component (not shown) being located on theheadend 11, preferably in the control system 232 (FIG. 2). A SAMdatabase 360 (i.e., structured data such as a database or datastructure) in DRAM 352 includes a data structure of services and a datastructure of channels that are created and updated by the headend 11.Herein, database will refer to a database, structured data or other datastructures as is well known to those of ordinary skill in the art. Manyservices can be defined using the same application component, withdifferent parameters. Examples of services include, without limitationand in accordance with one implementation, presenting televisioninstances (available through a WatchTV application 362), pay-per-viewevents (available through a PPV application 364), digital music (notshown), media-on-demand (available through an MOD application 363), andan interactive program guide (IPG) 397. In general, the identificationof a service includes the identification of an executable applicationthat provides the service along with a set of application-dependentparameters that indicate to the application the service to be provided.As an example, a service of presenting a television instance (mediacontent instance) could be executed by the WatchTV application 362 witha set of parameters specifying HBO to view HBO or with a separate set ofparameters to view CNN. Each association of the application component(tune video) and one parameter component (HBO or CNN) represents aparticular service that has a unique service I.D. The SAM client 357also interfaces with the resource manager 367 to control resources ofthe DHCT 16.

Applications can also be downloaded into DRAM 352 at the request of theSAM client 357, typically in response to a request by the user or inresponse to a message from the headend 11. In the example DHCT memoryillustrated in FIG. 3B, DRAM 352 includes a media-on-demand application(MOD) 363, an e-mail application 365, a PVR application 377, and a webbrowser application 366. It should be clear to one with ordinary skillin the art that these applications are not limiting and merely serve asexamples for embodiments of the invention. Furthermore, one or more DRAMbased applications may be resident, as an alternative embodiment, inFLASH memory 351. These applications, and others provided by thesubscriber television system operator, are top-level software entitieson the network for providing services to the user.

In one implementation, applications executing on the DHCT 16 work withthe navigator 355 by abiding by several guidelines. First, anapplication utilizes the SAM client 357 for the provision, activation,and suspension of services. Second, an application shares DHCT 16resources with other applications and abides by the resource managementpolicies of the SAM client 357, the operating system 353, and the DHCT16. Third, an application handles situations where resources are onlyavailable with navigator 355 intervention. Fourth, when an applicationloses service authorization while providing a service, the applicationsuspends the service via the SAM (the navigator 355 will reactivate anindividual service application when it later becomes authorized).Finally, an application is designed to not have access to certain userinput keys reserved by the navigator 355 (i.e., power, channel+/−,volume+/−, etc.).

The MOD application 363 provides the user with lists of available mediacontent titles for each media content instance to choose from and withmedia content instances requested by the user. The MOD application 363provides media content to the user by engaging, typically, in a directtwo-way IP (Internet Protocol) connection with VOD content servers (notshown) that would be located, in one embodiment, in the headend 11.

An executable program or algorithm corresponding to an operating system(OS) component, or to a client platform component, or to an application,or to respective parts thereof, can reside in and execute out of DRAM352 and/or FLASH memory 351. Likewise, data input into or output fromany executable program can reside in DRAM 352 or FLASH memory 351.Furthermore, an executable program or algorithm corresponding to anoperating system component, or to a client platform component, or to anapplication, or to respective parts thereof, can reside in FLASH memory351, or in a local storage device (such as the storage device 373)externally connected to or integrated into the DHCT 16 and betransferred into DRAM 352 for execution. Likewise, data input for anexecutable program can reside in FLASH memory 351 or a storage deviceand be transferred into DRAM 352 for use by an executable program oralgorithm. In addition, data output by an executable program can bewritten into DRAM 352 by an executable program or algorithm and betransferred into FLASH memory 351 or into a storage device. In otherembodiments, the executable code is not transferred, but instead,functionality is effected by other mechanisms.

Referring again to FIG. 3A, the DHCT 16 may also include one or morewireless or wired interfaces, also called communication ports 374, forreceiving and/or transmitting data to other devices. For instance, theDHCT 16 may feature USB (Universal Serial Bus), Ethernet (for connectionto a computer), IEEE-1394 (for connection to media content devices in anentertainment center), serial, and/or parallel ports. The user inputsmay be, for example, provided by an input device including a computer ortransmitter with buttons or keys located either on the exterior of theterminal or by a hand-held remote control device 380 or keyboard thatincludes user-actuated buttons, or even aural input (e.g., voiceactivated).

The DHCT 16 includes at least one storage device 373 to provide storagefor downloaded media content. The storage device 373 can be an opticalstorage device or a magnetic storage device, and is preferably a harddisk drive. The storage device 373 comprises storage for media contentand/or data that can be written to for storage and later read from forretrieval for presentation. The storage device 373 preferably includestwo hard disks 300 and 301, with each including a corresponding bufferspace TSB1 376 and TSB2 378, as will be explained further below.Alternatively, the DHCT 16 can be coupled to two storage devices, eachwith one hard disk. Alternatively, a storage device can be used thatuses different buffer spaces on one hard disk, or the storage device caninclude more than two hard disks, or platters. Throughout thisdisclosure, references relating to writing to or reading from thestorage device 373, or references regarding recordings from or to thestorage device 373 will be understood to mean that such read or writeoperations are occurring to the actual medium (for example, the harddisk 300 and/or 301) of the storage device 373. The storage device 373is also comprised of a controller 379 that receives operatinginstructions from a device driver 311 of the operating system 353 (asdescribed below) and implements those instructions to cause read and/orwrite operations to the hard disks 300 and/or 301.

The device driver 311 communicates with the storage device controller379 to format the hard disks 300 and 301, causing the hard disks to bedivided radially into sectors 301 and concentric circles called tracks302, as illustrated by the schematic diagram n of the example hard disk300 in FIG. 3C. It will be understood to one having ordinary skill inthe art that the discussion that follows pertains to hard disk 301 aswell as hard disk 300. Note from FIG. 3C that the same number of sectors304 per track 302 are illustrated, but other embodiments with adifferent number tracks per side, sectors per track, bytes per sector,and in different zones of tracks, are within the scope of the preferredembodiments of the invention. The sector 304 is the basic unit ofstorage on the hard disk 300. In one implementation, each sector 304 ofa hard disk 300 can store 512 bytes of user data. While data ispreferably stored in 512-byte sectors on the hard disk 300, the cluster,such as example cluster 303, is typically the minimum unit of datastorage the operating system 353 uses to store information. Two or moresectors on a single track make up a cluster.

Referring again to FIGS. 3A and 3B, the storage device 373 is preferablyinternal to the DHCT 16, coupled to a common bus through thecommunication interface 375, preferably an integrated drive electronics(IDE) interface or small computer system interface (SCSI), althoughIEEE-1394 or USB can be used. In other embodiments, the storage device373 can be externally connected to (and thus removable from) the DHCT 16via the communication port 374 implemented as IEEE-1394 or USB or as adata interface port such as a SCSI or an IDE interface. In oneimplementation, under the auspices of the real-time operating system 353(as described below) and executed by the processor 344, and incoordination with the personal video recording (PVR) application 377,the device driver 311, and the device controller 379 (the latter threecomponents described below), downloaded media content (herein understoodto also refer to other types of data, in addition to, or instead of,media content instances) are received in the DHCT 16 via thecommunications interface 342, processed as described above, and storedin a temporary cache (not shown) in memory 349.

The temporary cache is implemented and managed to enable media contenttransfers from the temporary cache to the storage device 373, or, inconcert with the insertion of a newly arriving media content into thetemporary cache. In one implementation, the fast access time and highdata transfer rate characteristics of the storage device 373 enablesmedia content to be read from the temporary cache in memory 349 andwritten to the storage device 373 in a sufficiently fast manner.Orchestration of multiple simultaneous data transfer operations iseffected so that while media content is being transferred from the cachein memory 349 to the storage device 373, new media content is receivedand stored in the temporary cache of memory 349. In otherimplementations, the downloaded media content is received through thecommunications port 374 in the DHCT 16 and then transferred directly tostorage device 373, thus bypassing the temporary cache.

The operating system 353, the device driver 311, and the controller 379communicate under program execution in the processor 344 and/or via theinterrupt and messaging capabilities of the DHCT 16 and thus cooperateto create a special file in one of the hard disk sectors in each harddisk 300 and 301 called a file allocation table (FAT) (not shown). TheFAT is where the operating system 353 stores the cluster and fileinformation about each of the hard disks 300 and 301, and which clustersare assigned and associated with a file and thus used to store whichmedia content instance files. The operating system 353 can determinewhere a file's data is located by using the directory entry (not shown)for the file and the entries of the FAT. The directory entry givesinformation about a directory such as its related files andsubdirectories and create time, and special permissions. A FAT entrydescribes the physical locations of data associated with a media contentdownloaded to the hard disks 300 and 301 of the storage device 373. TheFAT also keeps track of which clusters are free, or open, and thusavailable for use. Updates to the FAT are provided for by the operatingsystem 353, or the device driver 311, or a combination of both. Writesto each of the hard disks 300 and 301 are coordinated between the PVRapplication 377 (described below), the operating system 353, the devicedriver 311, and the storage device controller 379.

The PVR application 377, the operating system 353, and the device driver311 execute respective programmed instructions in the processor 344. Theprocessor 344, the storage controller 379, and the demultiplexing system315 communicate via interrupt and messaging capabilities of the DHCT 16.The PVR application 377, in communication with operating system 353, thedevice driver 311, the storage device controller 379, and thedemultiplexing system 315, effects retrieval of compressed videostreams, compressed audio streams, and data streams corresponding to oneor more media content instances from the storage device 373. Theretrieved streams are deposited in an output cache in the storage device373 and transferred to DRAM 352, and then processed for playbackaccording to mechanisms well known to those having ordinary skill in theart. In some embodiments, the media content instances are retrieved androuted from the hard disks 300 and/or 301 to the video and audiodecoding system 323 and 325 simultaneously, and then further processedfor eventual presentation on a display device or other device.

The PVR application 377 provides for media content recordingfunctionality by enabling the temporary writing to, and if requested,more permanent recording (i.e., relatively permanent) to the storagedevice 373. Media content can be transmitted (or downloaded) from aremote location, such as, for example, a remote server located in thehead end 11, or from a home communication network, or from otherconsumer electronic devices. Downloaded media content that is receivedat each tuner of tuner system 345 is temporarily buffered, or stored, onthe hard disk of the storage device. The corresponding space on eachhard disk is called a buffer space, or a time shift buffer (TSB). In apreferred embodiment, each tuner in tuner system 345 has a respectiveTSB. In one implementation, tuner1 354 receives media content forbuffering to TSB1 376. Likewise, the second tuner 358 receives mediacontent for buffering to TSB2 378. Moreover, media instances sourcedfrom a device such as a camera attached to the DHCT 16 via thecommunication port 374 has a respective TSB (not shown). Note thatbuffering is understood to mean temporarily storing media content,received from a local attached device, or either from reception of abroadcast digital channel, and/or a digital compressed version of abroadcast analog channel, and/or data, into the buffer spaces (or TSBs)of the storage device 373.

Under normal operation, the PVR application 377 effectively associates atemporary recording designation with the media content received into theTSBs. The media content stored in the TSBs will either be deleted (i.e.,the clusters storing the media content will be configured as writeablefor eventual write operations that overwrite the media content withinthose clusters) or retained (through election by the user, as oneexample) as a permanent recording. A permanent recording will beunderstood to include media content that is stored for an extendedperiod of time as decided by the user. Permanent recordings are storedin non-buffer clusters (i.e., not in clusters assigned to the TSBs) thatare not used for the TSBs in instances when the user elects in advanceto make a scheduled recording of a media content instance that has notyet been tuned to at the DHCT 16. A permanent recording can also beachieved by selecting a media content instance stored in the TSBs anddesignating the media content instance as permanent. In this latterimplementation, the designated media content is stored in clusters thatare configured from TSB clusters to permanent recording clusters(non-buffer clusters). To compensate for the re-designation of clustersto a permanent recording, the device driver 311 preferably assigns andassociates an equivalent number of clusters to the TSB that it obtainsfrom a pool of available unused and/or writeable (e.g., repossessed)clusters thus permitting continuance of normal TSB behavior andmanagement. Thus, permanent recordings will preferably be more permanentthan media content in the TSBs, and permanent recordings can eventuallybe deleted from the disk space, typically at the explicit request of auser, as one example.

There is a duration associated with the TSBs, which represents how muchdata is held by the TSBs. This duration could represent, in oneembodiment, actual media content instance time. The PVR application 377,in such a time-duration embodiment, will preferably maintain asubstantially constant buffer space capacity suitable for a certainduration of media content instance time, for example, 3-4 hours worth ofmedia content instances. Media content instance-time tracking is relatedto hard disk space tracking if a constant data rate, or buffering rate,is assumed or estimated. In a preferred embodiment, the duration of theTSBs represents hard disk space. The PVR application 377 can set abuffer size capacity, for example 3 gigabytes (GB), and then track thedisk space used for the TSBs to ensure a substantially constant TSBcapacity. For example, before the PVR application 377 effects a write tothe storage device 373, it can query the device driver 311 (through theoperating system 353) to determine the available hard disk space. Afterthe write operation, the PVR application 377 again can poll the devicedriver 311 to get an update on available hard disk space.

The TSBs can be managed according to several mechanisms. In oneembodiment, each media content instance that is received at either ofthe tuners of tuner system 345 prompts the PVR application 377 to causeeach media content instance to be downloaded to the hard disk 300 or 301and associated as a media content instance file under a designated mediacontent instance filename. This media content instance filename isrecorded in a FAT that maintains a list of the corresponding clustersstoring the media content instance file. The PVR application 377 alsocreates a management file that maintains a data record that preferablypoints to the corresponding filename and includes a data record thatincludes, among other elements, guide data and the receipt time of thedownloaded media content instance. The guide data includes the scheduledstart time and stop time of the downloaded media content instance aswell as other attributes and information that pertain to the mediacontent instance.

The receipt of the downloaded media content instance is also recorded bythe PVR application 377 (through coordination with the operating system353 and an internal clock 372) as a real-time value. The PVR application377 is either alerted to the start of a media content instance, in oneimplementation, from a keypress event (e.g., when a user tunes to adesired display channel). In another implementation, the PVR applicationcan use a polling or timing mechanisms (via timer 371, as one example)in cooperation with the internal real-time clock 372 and guide data. ThePVR application 377 provides the operating system 353 with the scheduledstop time (from guide data, such as from an interactive program guide)of the downloaded media content instance in order to set up a timerinterrupt (or in other embodiments, polls the operating system 353) withthe operating system 353. The operating system 353, in coordination withthe real-time clock 371 within the DHCT 16, alerts the PVR application377 (FIG. 3B) to the end of the received media content instance.

Further, the PVR application 377 preferably maintains the managementfiles with an organization mechanism such as a linked list, wherein eachmanagement file is associated with each of the media content instanceslocated on the hard disks 300 and 301. Read requests for one of thedownloaded media content instances in the TSB 378 occurs by the PVRapplication 377 searching the linked list for the requested mediacontent instance, and providing a graphics user interface (GUI) (notshown) on a display screen based on the information maintained in thecorresponding management file. Furthermore, a bi-directional link-listmechanism can be employed for arbitrary entry and to search forward orbackward in relation among media instances.

Further information pertaining to this embodiment for creating andmaintaining the TSBs can be found in the patent application entitled,SYSTEM AND METHOD FOR CONTROLLING SUBSTANTIALLY CONSTANT BUFFER CAPACITYFOR PERSONAL VIDEO RECORDING WITH CONSISTENT USER INTERFACE OF AVAILABLEDISK SPACE, filed Dec. 6, 2001 under Ser. No. 10/010,270 and assigned toScientific Atlanta, herein incorporated by reference.

Another embodiment for maintaining and managing the TSBs includesassociating a single file for each TSB, and controlling the allocationand deallocation of clusters in the disk space at the device driver 311level. In this embodiment, further described in the patent applicationentitled, DISK DRIVER CLUSTER MANAGEMENT OF TIME SHIFT BUFFER WITH FILEALLOCATION TABLE STRUCTURE,” filed Dec. 5, 2001 under Ser. No.10/005,628 and assigned to Scientific Atlanta, herein incorporated byreference, the PVR application 377 requests the allocation of disk spacefor a single file for each TSB. For each TSB 378, the device driver 311,implemented as either a separate software module, or integrated with theoperating system 353, allocates enough clusters and assigns them to therespective file to meet the size requirement designated by the PVRapplication 377. Media content instances downloaded and written to theTSBs are preferably tracked by time. The device driver 311 provides asoftware generated pointer, called Normal Play Time (NPT), which pointsto locations within files and locations within media content instanceswithin those files. Based on the Lightweight Stream Control Protocol,NPT can be thought of as the clock associated with a video asset (asdistinguished from the real-time clock 372 for the DHCT 16).

For every file that is created for media content downloaded to thestorage device 373, an NPT is generated. There is an NPT for the readhead of the storage device 373 and for the write head of the storagedevice 373. For writing media content to the storage device 373 for anewly created file (e.g., a TSB1 file), an NPT is created for the writehead of the storage device 373 with an initial value of zero. In oneimplementation, the device driver 311 receives a periodic interrupt (forexample every 5-10 msec) set up by the PVR application 377 through thecomputer services of the operating system 353. This interrupt issynchronized with the internal real-time clock 372 of the DHCT 16 inorder to advance the pointer (i.e., the NPT) at a substantially constantrate. The NPT continues to increase in value (from an initial value ofzero) until the associated file is closed. For the read head of thestorage device 373, the NPT starts at 0 at the start of the file,advances in real time in normal play mode, advances faster than realtime in fast forward mode, decrements in rewind mode, and is fixed whenthe video is paused.

The PVR application 377 maintains a data structure for every downloadedmedia content instance. There are one or more data structures preferablymaintained on the hard disks 300 and 301 of the storage device 373, butthe data structures can also be maintained in memory 349. The datastructures include, for example, the NPT values defining the start andend times of the downloaded media content instance, the real-time valuescorresponding to the start and end times of the media content instances,as well as the corresponding media content instance guide data, amongother elements. The device driver 311 maintains the mapping between NPTand the cluster and sector locations of the media content in a separatelook-up table data structure (not shown) preferably located on the harddisks 300 and 301. In one embodiment, the device driver 311 can samplethe current write location (i.e., cluster and sector location providedby the storage device controller 379) as the write head of the storagedevice 373 advances and store that cluster and sector location in thelook-up table data structure along with a corresponding NPT value. Thissampling can occur, for example, every 5-10 msec. In an alternativeembodiment, the device driver 311 can record an initial sample andthrough an estimation algorithm (e.g., interpolation) estimate filelocations and locations within said files. When the PVR application 377references a particular media content instance (for example where a userseeks to rewind to a downloaded media content instance in the hard disk300), the PVR application 377 passes the stored start and stop NPTvalues for that media content instance to the device driver 311, and thedevice driver 311 determines the hard disk locations from the look-uptable data structure. The PVR application 377 correlates NPT read valuesfor locations within the media content instances to the real-time clockvalue. With the real-time start and stop values and guide datamaintained in a data structure, as well as the correlated read-NPT toreal-time values, the PVR application 377 can produce a GUI thatprovides the user with information that includes what portion of abuffered media content instance the user is currently viewing.

As described above, the user preferably permanently records from theTSBs by designating as permanent a currently viewed media contentinstance during real-time viewing or returning (e.g., rewinding) to anypart of a media content instance in the TSBs and selecting record from aremote device 380, or alternatively, from selecting a record button (notshown) on the DHCT 16. An example remote control device 380 to provideinput to the DHCT 16 is illustrated in FIG. 3D. A display channel isselected, and changed, by a user, typically via pressing a key or buttonon the remote control device 380. Rewind 388 and fast-forward 387buttons enable a user to access buffered media content instances in theTSBs 376 and 378. A record button 390 enables the user to designate aspermanently recorded any media content instance buffered into the TSBs376 and 378, as described below. A pause button 391 (and a stop button389) enables the user to pause a media content instance, or pause duringa search for a particular media content instance. A playback button 392enables the playback of a media content instance. “A” 381, “B” 382, and“C” 383 buttons can correspond to certain application-defined functionsthat have a corresponding “A”, “B”, or “C” symbol displayed in a GUIpresented on a display device. A list button 384 can be used to evokevarious PVR application 377 user interface screens. Also included is aselect button 393 for selecting an option on a display screen, and upand down arrows 394 and 395 for scrolling through displayed options.Many alternative methods of providing user input may be used including aremote control device with different buttons and/or button layouts, akeyboard device, a voice activated device, etc. The embodiments of theinvention described herein are not limited by the type of device used toprovide user input.

FIG. 4 is a schematic diagram illustrating an example scenario in a twotuner (and two buffer) system that would require the establishment ofpriorities for downloading media content from a plurality of displaychannels, in accordance with one embodiment of the invention. One ormore of these display channels can also be presented to a displaydevice, such as a television 341, as shown by the dotted line from thesecond display channel. For example, assume the user was initiallywatching media content of the first display channel, and then selected asecond display channel for display (while buffering and displaying thefirst display channel). This display of media content of the seconddisplay channel can be a time-shifted display (sourced from the buffer),or the buffering and the display can occur in parallel. For thedescriptions that follow, it will be assumed that the newly requesteddisplay channel will always be displayed in favor of the currentdisplay. Shown are two hard disks 300 and 301. These hard disks arepreferably located in the storage device 373, as described above. Thehard disk 300 includes a buffer space (TSB1) 376 for receiving andstoring downloaded media content from a first display channel. The firstdisplay channel media content is preferably provided from the headend 11(FIG. 2) to one of the tuners, for example tuner1 354 of tuner system345 (FIG. 3A). The second display channel can be received at tuner2 358of the tuner system 345. The hard disk 301 includes a buffer space(TSB2) 378 for receiving and storing downloaded media content of thesecond display channel. Alternatively, TSB1 376 and TSB2 378 can bebuffer space on a single hard disk (e.g., one physical hard disk, orother storage medium, partitioned to function and be controlled as two“logical” hard disks), or on disks in separate storage devices.

While tuner1 354 receives media content of the first display channel forstorage into TSB1 376 and display on the TV 341, assume a user changesfrom the first display channel to the second display channel. In orderto receive media content at tuner2 358, the operating system 353 (FIG.3B) preferably performs a resource query to determine if the resourcesexist to tune and buffer both display channels. For instance, if tuner2358 was currently resourced to perform a scheduled recording, then thesecond display channel, in one implementation, may not be received attuner2 358, and thus the content of the second display channel may haveto be received at tuner1 354 and TSB1 376 at the expense of the mediacontent stored in TSB1 376 and received from the first display channel.

In another implementation, if the second display channel is transmittedover the same center RF frequency as the first display channel, asdetermined by the operating system 353 (FIG. 3B) from a display channelnumber to center frequency association table (not shown) in memory 349(FIG. 3A), resourcing of tuner2 358 is not necessary and media contentof both the first and second display channel are received via tuner1 354and deposited into the respective TSB1 376 and TSB2 378.

Assume the user changed from the first display channel to the seconddisplay channel, and that the second tuner 358 is an available resource.The media content of the first display channel, in one embodiment, willnot be “deleted” (i.e., written over or its associated clusters madewriteable) but instead retained for now, and the media content (afterthe display channel change) will continue to be received at tuner1 354and downloaded into TSB1 376 from the first display channel. The pointin time when the user resources tuner2 358 to receive the second displaychannel is “marked” and stored in memory 349 and thereafter copied to aPVR application data structure (not shown) associated with the bufferspaces of the storage device 373 (FIG. 3A) when enough time of bufferingthe second display channel elapses. Buffering to storage device 373 ispreferably effected by the caching the data to memory 349 (FIG. 3A) andthereafter reading the respective data from memory 349 and writing it tostorage device 373. The buffering is timely orchestrated so thatpreviously deposited data to memory 349 is read while additional data isbeing written to memory. Further, a pointer to the location of the harddisk 300 where the media content of the first display channel isbuffered when tuner2 358 is resourced is also recorded in the datastructure to enable later access and/or retrieval, as described below.

In an alternate implementation, memory 349 (FIG. 3A) in DHCT 16 (FIG.3A) is of sufficient size to permit buffering of data up to apredetermined elapsed time required according to a threshold beforeproceeding to transfer the cached data in memory 349 to storage device373 (FIG. 3A). Consequently, less bookkeeping is required on the storagedevice 373.

The amount of elapsed time deemed to be sufficient is determined bycomparison to a first programmable threshold value. The threshold valuecan be preset at compilation time by the application developer. In onepreferred embodiment, the programmer programs the threshold to have aninitial default value that can be modified throughout the course of timeby the viewer according to the viewer's preference via an interactiveconfiguration application (not shown) in which the viewer makesselections in a displayed graphical user interface (GUI) by enteringinformation with key presses or by entering alphanumeric informationwith an input device such as a remote control device 380 (FIG. 3D). Forinstance, desired preferences and configuration can be entered as partof an overall general settings application 312 (FIG. 3B).

The PVR application 377 (FIG. 3B) recognizes the keypress eventassociated with the display channel change, and determines the time ofthe key press from time and clock provisions in the DHCT 16 (FIG. 3A)and from services of the operating system 353 (FIG. 3B). The time of thekey press is stored in memory 349 (FIG. 3B) and thereafter if enoughtime elapses, as defined by a first threshold, for example, whilebuffering the second display channel, the time of the key press is alsoannotated (written) into the storage device 373 with annotationsassociated with the respective media content. Annotations includeinformation required to retrieve the media content downloaded to thestorage device 373 (FIG. 3A). Such information includes the time thatthe media content was received, information to fulfill playback andother navigating modes, characteristics of the media content, elapsedtime of buffering, and a pointer to the location of the downloaded mediacontent, among other information. If enough time elapses, an addressmarker associated with the start of where the media contentcorresponding to the second display channel is downloaded is also storedon the hard disk 300 or 301 (FIG. 3A) in the storage device 373 (FIG.3A) as part of the media content's annotations. The PVR application 377stores these values in memory until it determines that sufficient time(according to a first threshold) has elapsed and then also stores themin the hard disk 300 or 301 by reading their respective information frommemory 349 and writing it to hard disk 300 or 301.

The PVR application 377 (FIG. 3B) waits until a next input stateregardless of whether enough time has elapsed to store annotations inthe storage device 373 (FIG. 3A). A next input state from a set ofpossible next input states includes a viewer's input such as a keypressevent that is possibly associated with returning to the first displaychannel (when that occurs). A next input state can alternativelycorrespond to a key press corresponding to the currently displayedchannel (that is, the second display channel) or to a third displaychannel. A key press that selects the second display channel while theuser is currently viewing the media content of the second displaychannel may be a viewer's mistake, in conventional television systems.However, in the preferred embodiments, it can actually signify a desiredeffect by the viewer such as to give precedence to buffering the seconddisplay channel over the buffering of a first display channel. In oneembodiment, this viewer desired precedence behavior for buffering thesecond display channel becomes effective indefinitely. In an alternateembodiment, the viewer desired precedence behavior for buffering thesecond display channel becomes effective if the viewer subsequentlyselects to display a third display channel within a specific amount ofelapsed time corresponding to less than a second threshold.

The return to the first display channel causes the PVR application 377(FIG. 3B) to, in one implementation, return to the point in the mediacontent instance that the user left off viewing the media contentassociated with the first display channel to go to the media content ofthe second display channel. In other implementations, according to aprogrammed default behavior or to a viewer's configured preference, theuser can be returned to the real-time tuned position to receive thecurrent media content, with the ability to rewind back to where the userleft the media content of the first display channel. The first displaychannel and the second display channel can download a single mediacontent instance to each of the buffer spaces 376 and 378 betweendisplay channel changes, or a plurality of media content instances canbe downloaded to each respective buffer space, depending on the amountof time, or the download duration, that the media content is received ineach respective buffer space. In other words, the user is free to changethe display channel at any point within or after a media contentinstance presentation, and thus at any point in time, either bufferspace can temporarily store, for example, a portion (e.g., 30 seconds)of a media content instance, or enough media content instances to reachbuffer space capacity, among other examples. Such buffering behavior isdetermined in part by a set of programmed thresholds, including a firstand a second threshold as described above. Alternatively, each thresholdin the set of thresholds can be fixed to respective empiricallydetermined values by the application developer. In another embodiment,some of the thresholds in the set may be programmed to be configurableand others to fixed values.

When the user decides to change display channels (e.g., switch to athird display channel), the media content of the third display channelcan go to either TSB1 376 or TSB2 378. In one embodiment, according to aprogrammed behavior, when the media content of the third display channelis downloaded to one of these buffer spaces, the media content alreadystored there is deleted (e.g., overwritten or made writeable) in orderto receive and store the media content of the third display channel. Auser can implement a preference as to which buffer space media contentto delete.

In other embodiments, a currently buffered display channel's mediacontent is deleted after a display channel change according to a set ofcontrolling rules based on the respective values of a set of inputvariables that effect one or more outcomes or resulting behaviors. Thecontrolling rules are programmed by the application developer and employmeasured input variables that preferably connote elapsed time asmeasured in the background throughout the course of time by the PVRapplication 377 (FIG. 3B). Relational input variables are also employedby the programmed controlling rules. The relational input variablesexpress respective comparisons of the value of an input variable typethat expresses elapsed time for a first display channel to the value fora second display channel. As a non-limiting example, a relational inputvariable may be the fraction obtained by division of the values of thetwo corresponding input variables being compared or their reciprocal.

The PVR application 377, the operating system 353, the controller 379,the general settings application 312, and the device driver 311 (FIGS.3A and 3B) execute respective programmed instructions in the processor344 (FIG. 3A). The communication between these entities is preferablyvia interrupt and/or messaging capabilities of the DHCT 16 as well as bysharing of data output by one of these entities and written in memory349 that serves as input to one or more of any of these entities byreading the data from memory 349. The data output by one or more ofthese entities can be input data to itself. Programmed controlling rulesare a programmed component part of the PVR application 377. Thecontrolling rules comprise ingredients employed in the preferredembodiments of the invention to make decisions, for example decisions asto priority of buffering and tuning resources. This rule-based system ofthe preferred embodiments includes variables that feed into theirantecedents, and each rule produces a consequence or a prediction. Theset of consequences may in turn be input to another set of rules toprovide an overall output, or the consequences may be input to othermechanisms (e.g., statistical classifiers, syntactical classifiers, orother inference engine mechanisms used with inference engines in expertsystems) to make a decision. As will be described further below,variables can be assigned coefficients. Consequences produced by therules can be assigned a weight as well. The weights can changethroughout the course of time, for example in a dynamic system. Ifprobability or a confidence/certainty factor is assigned to a variable(e.g., a favorites channel), then the rule based system can begenerically categorized as a fuzzy-set system.

The scope of outcomes or actions conducted by the execution of theprogrammed controlling rules, include one or more of the following:

-   -   A. Determination of available unemployed resources such as        tuners, TV displays to display the newly requested display        channel, storage device capacity (including the time shift        buffers) to store the media content of the newly displayed        channel, access capability to and/or from the storage device        (e.g., via interfaces), compression engines, and decompression        engines. Note that the access capacity may be an issue with high        definition television streams. For example, in an implementation        that includes a single hard disk drive, available bandwidth for        transfers to and from the hard disk through the IDE interface,        for example, can be limited, especially for high bit rates.    -   B. Determination of whether to discontinue a display channel        that is sourcing media content (that is being currently        buffered) to repossess a lacked resource that is required to        effect the viewer's newly requested display channel's media        content.    -   C. Upon determination of a need for discontinuation of a display        channel, selection of a currently buffered display channel        (selected display channel) to discontinue.    -   D. Upon the lack of an available tuner to receive another        display channel, discontinuation of sourcing the selected        display channel's media content via the tuner, and    -   E. Commencement of sourcing of the viewer's newly requested        display channel's media content via the repossessed tuner.    -   F. Discontinuation of buffering the currently buffered display        channel's media content in a TSB from a first tuner, and        deletion (or displacement) of that media content,    -   G. Continuation of buffering of a non-displaced display        channel's media content associated with a second tuner in a TSB,    -   H. Commencement of buffering into the repossessed TSB of the        viewer's newly requested display channel's media content,    -   I. Upon the lack of an available TV display to display another        display channel, discontinuation of display on the TV display of        the selected display channel's media content that is being        buffered,    -   J. Commencement of display on the TV of the viewer's newly        requested display channel's media content on the repossessed TV        display.

The order in the actions conducted can differ, and no particular orderis implied by the list A-J described above. A tuner resource changecomprises the discontinuation of receiving a display channel's mediacontent, and receiving the media content of another display channelrequested by the viewer. A display resource change comprises thediscontinuation of displaying a received display channel's media contentand displaying on the TV 341 the media content of a newly requesteddisplay channel. A buffer resource change comprises the discontinuationof a received display channel and deletion of the corresponding mediacontent that is buffered, in addition to buffering the media content ofanother received display channel in the TSB.

With continued reference to FIG. 4, if all the resources are availableto tune, buffer, and display the media content of the third displaychannel (i.e., newly requested display channel), no discontinuation isrequired in the signal flow path through the DHCT. However, if there isa conflict in resources used such that the current resources are fullyemployed for tuning, buffering, and/or displaying the first and seconddisplay channel media content, then the controlling rules of thepreferred embodiments will provide for a discontinuation preferably inreverse order (e.g., from display to source) to the order used toestablish a connection between resources to tune, display, and/or bufferthe media content, and connection in the forward order (e.g., fromsource to display) for receiving, buffering, and displaying the mediacontent for the newly requested display channel.

For the example implementations provided, it will be assumed that anewly requested display channel is to be both displayed on thetelevision 341 and buffered, with the understanding that the preferredembodiments can be used to accomplish either one of these operationsalone or in combination. A couple of considerations are worth noting inthe context of proper resource management. For example, according torules and precedences configured, and with continued reference to FIG.4, the second display channel may be discontinued from being displayed,but its buffering may continue. The first display channel that was notbeing displayed but only buffered may stop buffering, and its associatedtuner may discontinue sourcing the media content of the first displaychannel in favor of sourcing the newly requested display channel.Further, the media content of the first display channel downloaded tothe buffer can be deleted in favor of the media content of the newlyrequested display channel. Thus, although tuning, displaying, and/orbuffering media content from one display channel can be completelydiscontinued in favor of a newly requested display channel, it is alsopossible that the signal flow for both display channels (the first andthe second) will in some way be affected to provide resources for thenewly requested display channel media content. As described above, thediscontinuation in signal flow is preferably done in the reverse order(i.e., reverse to its forward connection), such that the display for thesecond display channel is discontinued first, and then the buffering andthen the tuning is discontinued for the first display channel, as oneexample.

Another consideration in resource management includes the fact thatdiscontinuation will vary in the signal flow path and the resourcesaffected, in some implementations, depending on whether the receiveddisplay channel is analog or digital. FIGS. 5-11 will now be used tofurther illustrate the signal flow paths through a DHCT, and inparticular, how resources are employed to receive (tune), buffer, and/ordisplay media content sourced from analog transmission signals anddigital transmission signals. The timing diagrams of FIGS. 5-11 willalso help to provide added understanding of the outcomes described abovein A-J.

FIG. 5 is a timing diagram that illustrates one example implementationfor resource connections for a digital signal flow path where there is adisplay of the media content with no buffering. Step 501 includesforwarding the digital transmission signal from a resourced tuner of thetuner system 345 to the signal processing system 314. At the signalprocessing system 314, the digital signal is preferably demodulated anddemultiplexed, and forwarded to the media engine 322 (step 502). Step503 includes decoding the signal in cooperation with media memory 305,and then the media content is readied and reconstructed (step 504) foroutput (via output stage 348 (FIG. 3A), as understood herein) to the TV341 (step 505). Discontinuation of the signal flow path, according tothe preferred embodiments, will preferably occur in the reverse order(e.g., steps 505, 504, 503, etc.), as is generally true for FIGS. 6-11that follow.

FIG. 6 is a timing diagram of one example implementation for bufferingand displaying media content in a digital signal path. Steps 601 through605 are similar to steps 501 through 505 described in association withFIG. 5. Step 610 preferably occurs in parallel to step 602, and includescaching the demultiplexed signal in DRAM 352. Step 611 includes routingthe signal from DRAM 352 to an interface 375, and step 612 includesrouting the signal to a time shift buffer in the storage device 373.

FIG. 7 is a timing diagram of one example implementation that includesdisplaying a time-shifted (i.e., buffered) digital signal. Step 701includes forwarding the digital signal to the signal processing system314 for demodulation and demultiplexing. The signal is then cached toDRAM 352 (step 702), routed to the interface 375 (step 703) and then tothe storage device 373 (Step 704). From the storage device 373, thesignal is routed back to the interface 375 (step 705), and then to themedia engine 322 (step 706). The media engine 322 and the media memory305 cooperate to decode the signal (step 707), and then the signal isreconstructed and conditioned for output (step 708), and then the signalis output to the TV 341 (step 709).

FIG. 8 is a timing diagram of one example implementation that includesbuffering the media content from one of the display channels to thestorage device 373. As shown, the digital transmission signal receivedat a tuner of the tuner system 345 is forwarded to the signal processingsystem 314 (step 801), cached to DRAM 352 (step 802), routed to theinterface 375 (step 803) and then to the storage device 373 (step 804).

FIGS. 9-11 will now be used to illustrate the signal flow path andresources employed for tuning, buffering, and/or displaying mediacontent modulated in an analog transmission signal. FIG. 9 is a timingdiagram illustrating an example signal flow path and resources employedfor decoding and displaying an analog signal. Step 901 includesforwarding the analog signal received at a tuner of the tuner system 345to the signal processing system 314, where it is demodulated andforwarded to the analog decoder 316 (step 902) for decoding. Theresulting decoded, digitized signal is then forwarded to the mediaengine 322 (step 903), and then forwarded to the media memory 305 (step904) where the signal is readied for output, and then forwarded to theTV 341 (step 905).

FIG. 10 is a timing diagram of one example implementation where theanalog signal is buffered and displayed in parallel processes. Step 1001includes forwarding the analog signal from the tuner system 345 to thesignal processing system 314, where it is demodulated and then forwardedto the analog decoder 316 (step 1002). From the analog decoder 316,processing occurs in two parallel paths. Step 1003 includes forwardingthe decoded digitized signal to the media engine 322, and then to steps1004 and 1005 that mirror steps 904 and 905 of FIG. 9. The otherprocessing path from the analog decoder 316 includes forwarding thedecoded digitized signal to the compression engine 317 (step 1010) forcompression, which occurs in cooperation with compression engine memory309 (step 1011), and then caching the compressed signal (step 1012). Thecompressed signal is then routed from DRAM 352 to the interface 375(step 1013), and then routed for storage in the storage device 373 (step1014).

FIG. 11 is a timing diagram of one example implementation where themedia content displayed is time shifted. Step 1101 includes forwardingthe analog signal received at the tuner system 345 to the signalprocessing system 314 for demodulation. The demodulated signal is thenforwarded to the analog decoder 316 (step 1102) where it is decoded, andthen forwarded to the compression engine 317 (step 1103) for compressionin cooperation with compression engine memory 309 (step 1104). From thecompression engine 317, the signal is then cached in DRAM 352 (step1105) and transferred to the interface 375 (step 1106) and then routedto the storage device 373 (step 1107). From the storage device 373, thesignal is then routed to the interface 375 (1108) and then to the mediaengine 322 (step 1109), where it undergoes decoding (step 1110) incooperation with media memory 305, and then the signal is reconstructedand output processed (step 1111), and then the signal is output to theTV 341 (step 1112).

Thus as shown, the management of resources for tuning, displaying,and/or buffering media content from a plurality of display channelsincludes, in addition to the considerations mentioned above, determiningwhether the resources are processing analog signals, digital signals, ora combination of both. FIG. 12A is a flow diagram of an example resourcemanagement process that can be implemented when the first and/or seconddisplay channel signal flow needs to be discontinued, in whole or inpart, to provide for the tuning, buffering and display of a newlyrequested display channel. Assume that the desired signal flow for thenewly requested display channel is as shown in the configurationillustrated in FIG. 6 (e.g., display in parallel to buffering), or inother embodiments, the configuration shown in FIG. 7 (time-shifteddisplay). Step 1201 provides that media content is provided in a firstdisplay channel for display to the display device and in parallel, forbuffering to a storage device, much like the configuration shown in FIG.6. Step 1202 provides that the second display channel is now beingdisplayed and buffered (which results in discontinuation of the displayof the media content of the first display channel), and the firstdisplay channel is resourced within a configuration that appears muchlike the configuration shown in FIG. 8. Similar actions andconfigurations can apply for analog signals, as will be described below.

Step 1203 includes receiving a request for a new display channel. Forpurposes of discussion, it will be assumed that the new display channelis provided as a digital signal, with the understanding that the stepsprovided herein can be generally applied for an analog signal, or acombination of analog and digital signals. Step 1204 includesdiscontinuing the display of the media content of the second displaychannel on a display device (e.g., TV). For example, if the seconddisplay channel was currently providing media content to the displaydevice, such as that shown in the timing diagram of FIG. 6, thefollowing forward path steps would be reversed, preferably in the ordergiven: steps 605, 604, 603, and then 602. At this stage, the first andthe second display channel would have a forward signal path that closelyresembles FIG. 8 for a digital signal (or steps 1001, 1002, 1010 through1014 of FIG. 10 for an analog signal).

Step 1205 includes determining a precedence for resourcing a newlyrequested display channel according to a set of controlling rules, aswill be described below. If the rules mandate that the first displaychannel has precedence, then discontinue the buffering of the mediacontent of the second display channel (step 1206, FIG. 12B). Accordingto the example configuration shown in FIG. 6, such an action wouldresult in discontinuing the signal flow path according to the followingorder: steps 612, 611, 610, 602, and 601 (or steps 1014-1010, 1002, and1001 of FIG. 10 for an analog signal). Step 1207 (FIG. 12B) includesusing the tuner resources, the buffer resources, and the displayresources previously employed for the second display channel to resourcethe media content of the newly requested display channel.

Referring to FIG. 12C, with continued reference to FIG. 12A, if therules mandate that the second display channel has precedence, thenbuffering for the second display channel (for example, as shown in steps801 through 804 of FIG. 8 for a digital signal, or steps 1001, 1002,1010-1014 of FIG. 10 for an analog signal) will continue and the firstdisplay channel buffering path will be discontinued (step 1208). Step1209 includes using the tuner resources, the buffer resources, and thedisplay resources previously employed for the first display channel toresource the media content of the newly requested display channel.

In one implementation, the repossession of “buffering resources” of thereceived display channel to be displaced uses a form of bookkeeping. Inone embodiment, the point on the hard disk (e.g., 300 or 301, FIG. 3A)where the media content to be deleted started will preferably berecorded (for example in the PVR data structure or in annotations in thestorage device 373 (FIG. 3A)) such that the newly requested displaychannel media content will start at the point where the deleted mediacontent started. Another form of bookkeeping that can be used in otherembodiments includes subtracting the amount of total buffer capacityafter such deletion. As described briefly above, the determining ofprecedence relies preferably on a set of controlling rules, which inturn rely on a set of input variables, and/or user inputted preferences.One of the input variables to the controlling rules, including thoserules that control discontinuation of buffering of a display channel'smedia content, can be the length of contiguous time of buffering thedisplay channel's media content (and deletion of buffered mediacontent). Alternatively, the total time of buffering a respective mediacontent instance (i.e., not necessarily contiguous time) can beemployed.

Another input variable can be the length of time that a buffered displaychannel's media content is displayed on TV. Whether a buffered displaychannel's media content is currently displayed or last displayed on TVmay cause this input variable to be weighted more significantly in thecontrolling rules. Hence, the multiplicative coefficient of an inputvariable may be dynamically adjusted according to a user's viewingpatterns. The relationship between the length of buffering elapsed timebetween media content of a first display channel currently beingbuffered to media content of a second currently buffered display channelcan also be another input variable.

The relationship between the length of buffering elapsed time of adisplay channel's media content currently being buffered to its totaltime displayed on TV throughout the course of buffering can also be aninput variable. Another input variable to the controlling rules can bewhether a display channel currently being buffered is included in afavorites channel list, such as a list of preferred display channelsselected or entered by the viewer during the course of a configurationsession. A favorites channel list, as well as all preferences andconfigurations aforementioned herein are stored in memory (e.g., DRAM352) and in non-volatile memory, such as FLASH memory 351 (FIG. 3A) forits recovery in the event of a power outage. The storage device 373(FIG. 3A) can also serve for storing preferences and configurations andrecovery upon power-up. Whether the favorites channel list influencesthe controlling rule is preferably a configuration and/or preferenceentered by the viewer during a configuration session.

In one embodiment, when the favorites channel list is employed as inputto the controlling rules, a different set of controlling rules isexecuted. Alternate values for thresholds that control relational inputvariables can be employed when the favorites channel list is part of theinput to the controlling rules. Hence, if a display channel beingbuffered is in the favorites channel list, it will influence thecontrolling rules in a way more towards continuing its buffering (orequivalently, less likely of being displaced and discontinued due tosourcing the tuner and respective TSB for media content of a newlyrequested display channel).

An input variable may be designed to exhibit a non-linear range whencontrolled by a respective threshold or set of thresholds. A first inputthreshold is preferably assigned to control the value of a firstvariable. A first type of input variable may be assigned a value of “nosignificance” (e.g., zero) if below its respective first controllingthreshold value. Furthermore, the value of a second type of inputvariable may be controlled with a first controlling respective thresholdand a second respective controlling threshold. If the value of thesecond type of input variable is above or equal to a first respectivecontrolling threshold but below a second respective controllingthreshold value, it retains its original value. Furthermore, the valueof a third type of input variable may be controlled with a firstrespective controlling threshold and a second respective controllingthreshold but may be assigned a maximum value when its value is above asecond respective controlling threshold value. As would be understoodand appreciated by those having ordinary skill in the art, thecomparison of an input variable's value to a threshold value may bebased on programmable operations, including “if less than the value”,“less than or equal to”, “greater than”, “greater than or equal to”,“equal”, and/or “not equal.”

A fourth type of input variable may be controlled by assigning arespective “no significance” value indirectly or directly per a viewer'sinput. A fifth type of input variable may be controlled by assigning arespective “no significance” value indirectly or directly per a viewer'sinput to configure a desired buffering, tuning and/or display behaviorduring a configuration session. A sixth type of input variable may becontrolled by assigning a respective “maximum value” indirectly ordirectly per a viewer's input. A seventh type of input variable may becontrolled by assigning a respective “maximum value” indirectly ordirectly per a viewer's input to configure a desired buffering, tuningand/or display behavior during a configuration session. In this way, thevalue of some and possibly all input variables can be modified to anon-linear range of values according to their actual value. The actualvalue of an input variable can be a measured value, a user input value,or a default value assigned by the programmed application. Each inputvariable may be further weighted multiplicatively with a respectivecoefficient that pertains to the importance of the respective inputvariable with respect to the complete set of input variables employed bythe controlling rules. For example, a first controlling rule has a firstmultiplicative coefficient for a first input variable and a secondcontrolling rule has a second multiplicative coefficient for the samefirst input variable.

Throughout the course of time, the PVR application 377 (FIG. 3B) employsOS services such as time posting and clock access to allow updating ofvalues for each respective input variable in the set of input variables,and to be updated according to the “time posting granularity” of the OS353 and according to the granularity of timer 371 and clocks 372 (one isshown) of DHCT 16. Values of input variables are stored in memory 349(FIG. 3A) with annotations pertaining to a file in the storage device373 (FIG. 3A).

Upon a viewer's input entered via an input device such as a remotecontrol device 380 (FIG. 3D), the PVR application 377 executes on theprocessor 344 (FIG. 3A) to enter a machine state wherein the PVRapplication 377 (FIG. 3B) assesses and determines available resourcessuch as (1) tuners for sourcing media content of a display channelselection by the viewer, (2) TV display for displaying a displaychannel's media content, (3) compression engines for compressing analogsignals, (4) decompression engines for decoding digital signals, (5)communication interfaces for access to and from the storage device, and(6) TSBs for buffering the respective display channel's media content.Determination of resources is part of the controlling rules in oneembodiment. When the PVR application 377 determines the lack of arequired resource, controlling rules are executed to effect the desiredchange according to the viewer's input requesting a new display channel,a prior entered viewer's configuration and prioritization, and/oraccording to set of input variables.

Prior to the execution of the controlling rules, pre-processing of theapplicable input variables is preferably conducted. The pre-processingmodule 385 (FIG. 3B) includes processing of the controlling rules and ispreferably included in the PVR application 377 (FIG. 3B), althoughsimilar functionality can be found in other applications or as aseparate module. In the pre-processing module 385, the respective valuesof input variables is read from memory 349. For an applicable inputvariable, its respective value is compared to one or more thresholdsassigned to that particular input variable and a modified value for theinput variable is obtained. Hence, the pre-processing module 385 mapsthe actual value of each input variable required to be modified to adesired range according to the predetermined set of thresholds assignedto control the respective input variable. Thereafter, each pre-processedinput variable is multiplied by its respective weight coefficient andthe set of controlling rules are executed to obtain one or more outcomesthat effect one or more resource changes.

The following description will include an example implementation, basedon FIG. 4, using some input variables to illustrate a rule-based systemthat determines priority of resources to tune, buffer, and display athird display channel when two other display channels are consuming theresources needed for the third display channel. One way to prioritizewhich buffer space of the storage device 373 (FIG. 3A) to delete ofmedia content is to prioritize the cumulative media content in eachbuffer space by evaluating input variables such as download duration.For example, if the user was viewing the first display channel for 5hours, and then decided to “channel surf” (i.e., change display channelsin brief succession) over 1 through “N” display channels, then it isprobable that the content downloaded from the first display channel isof higher significance, or of a higher priority, than the media contentdownloaded from the surfed display channels. Thus, with each displaychannel change, a tuner and buffer conflict arises whereby media contentdownloaded from prior display channels into TSB1 376 and/or TSB2 378 areat risk of being deleted to accommodate the download of the newlyrequested display channel. It will be assumed that the most recentlytuned display channel will be displayed. The conflict of tuning andbuffering can be addressed, in one implementation, by establishing asystem that prioritizes the download duration to each buffer spaceaccording to controlling rules.

In the preferred embodiments, the buffering duration of the mediacontent of the first display channel up to the point of the displaychannel change (to the second display channel) is compared to thebuffering duration of the media content of the second display channel.For example, the user can be viewing a series of media content instancesover a span of hours on the first display channel. The user then decidesto look at the score of a football game on the second display channel.The point in the presentation of the media content instance of the firstdisplay channel when the user switched to the second display channel is“marked”, and this “mark”, the buffering duration, and the displayedduration for the first display channel are stored in a PVR datastructure with its pertinent annotations (not shown). The user is nowviewing the football game on the second display channel, which ispreferably received at tuner2 358 and buffered to TSB2 378. The mediacontent of the first display channel continues to be downloaded to TSB1376. Assume the user waits a few minutes before the score comes up onthe screen display for the football game, and then decides to go to athird display channel.

Assuming the two tuner DHCT illustrated in FIG. 4, the user selects thethird display channel on his or her remote control device 380 (FIG. 3D).The PVR application 377 (FIG. 3B) executes the set of controlling rulesand according to the outcome of the rules, makes a determination as towhich tuner (tuner1 354 or tuner2 358) to resource as well as therespective applicable behavior to effect. The PVR application 377 makesthis determination by executing the programmed controlling rules thateffectively compare the buffering duration (stored in the PVR datastructure) of the first display channel with the buffering duration ofthe second display channel (the football game) by the pre-processing(via the pre-processing module 385 (FIG. 3B)) of applicable inputvariables and execution of controlling rules. Since the difference inbuffering durations is measurable in hours, the second display channelis discontinued, the second tuner 358, in one implementation, is thenresourced for the third display channel and the associated bufferedmedia content (i.e., the game in TSB2 378) is deleted in order toreceive and store the media content of the third display channel.

If shortly after switching to the third display channel, the userdecides to switch to a fourth display channel, the PVR application 377(FIG. 3B) does a similar evaluation of buffering durations. Thebuffering duration of the first display channel (stored in the PVR datastructure) is compared to the buffering duration for the third displaychannel. Again, in one implementation, due to the large difference inbuffering duration (or because the buffering duration of the thirddisplay channel did not meet sufficient elapsed time according to afirst threshold), the third display channel is discontinued, the secondtuner 358 is again resourced for the fourth display channel, and theTSB2 media content of the third display channel is deleted to receivethe media content of the fourth display channel, while the media contentof the first display channel continues to be buffering and retained inTSB1 376.

FIGS. 13-17 are a series of flow charts illustrating steps forprioritizing between tuner and buffer resources based on a plurality ofbuffering durations in order to address the example scenario of FIG. 4,in accordance with several embodiments of the invention. The blocks inthe flow charts should be understood as representing modules, segments,or portions of code which include one or more executable instructionsfor implementing specific logical functions or steps in the process, andalternate implementations are included within the scope of the preferredembodiment of the present invention in which functions may be executedout of order from that shown or discussed, including substantiallyconcurrently or in reverse order, depending on the functionalityinvolved, as would be understood by those reasonably skilled in the artof the present invention.

With continued reference to FIG. 4, FIG. 13 is a flow chart thatestablishes an arbitrary starting point for prioritizing the bufferingdurations to the first buffer (TSB1 376) and the second buffer (TSB2378). Step 1302 includes receiving the media content of the firstdisplay channel (via tuner1 354) into the first buffer (TSB1 376), anddisplaying the media content on the TV 341. Thus, as a non-limitingexample, a two-tuner system is assumed, and tuner1 354 is employed toreceive media content of the first display channel. Upon a viewer'sinput via an input device (e.g., a remote control device 380, FIG. 3D)to display a second display channel's media content, step 1304 includesreceiving the media content from a second display channel (via tuner2358) into the second buffer (TSB2 378), and displaying the media contenton the TV 341. The second tuner (tuner2 358) is assumed to be anavailable resource, and thus receives the media content of the seconddisplay channel. The newly requested display channel will preferablyhave display resource precedence over the currently displayed displaychannel.

Step 1306 includes receiving user input requesting a third displaychannel. Unless the DHCT 16 contains additional tuners, a conflictarises, since one of the tuners (354 or 358) has to be resourced toreceive the media content of the third display channel for display onthe TV 341 (FIG. 4). This example scenario assumes that no other bufferresource conflicts are present, for instance from a scheduled permanentrecording or from preference filter mechanisms, among others. Otherwise,additional constraints or behavior would be enacted based on the outcomeof the execution of the programmed controlling rules. Some conflicts,when they arise, can give rise to conflict barkers that are presented ona display screen to give the user the opportunity to resolve theconflict. Other conflicts can be automatically resolved by execution ofthe programmed controlling rules. In some embodiments, a system settingsmenu (not shown) can be utilized at start-up or at times convenient tothe user that enables the user to select and/or configure prioritiesbetween these and other conflicts that may arise. Assuming that the DHCT16 has only two tuners, step 1308 includes a decision to be made by thePVR application 377 (FIG. 3B). Namely, the PVR application 377, uponreceiving a request for a display channel change to a third displaychannel, decides whether media content of the first two display channelswas buffered for a minimum threshold buffering duration prior to therespective display channel changes. The determination of which displaychannel did not meet the minimum buffering threshold will be left forstep 1410 of FIG. 14, as described below.

If a minimum buffering duration threshold was not met for the bufferingof the media content to its respective buffer, then the prioritizingcontinues to point A in FIG. 14, otherwise to point B in FIG. 15.Continuing the example at point A in FIG. 14, the PVR application 377decides whether the media content buffered to either buffer was bufferedover at least a minimum threshold duration (step 1410). If a bufferingduration threshold was met for the buffering of the media content to onebuffer, then step 1412 includes the steps of resourcing the tuner (forthe third display channel media content) that is sourcing the displaychannel for which the buffered media content does not satisfy theminimum duration according to a first threshold. In turn, the mediacontent buffered for less than the minimum threshold is displaced withthe media content buffered from the third display channel, while themedia content buffered for a minimum threshold duration is retainedallowing for a continued tuning and buffering operation.

If the buffering of the media content to either buffer failed to meet aminimum threshold duration, then either tuner1 354 or tuner2 358 (FIG.3A) is resourced for the third display channel and the media contentfrom either buffer is displaced while retaining the media content in thenon-displaced buffer. At this point, other input variables (as describedabove), can be employed to provide a decision as to priority. In oneembodiment, the media content consuming the least buffered space isdisplaced. In another implementation, the latest displayed channel mediacontent is retained. In yet another embodiment, the last displayedchannel (e.g., the first display channel media content) is retained whenthe viewer has pressed the key for the current display channel mediacontent being displayed (e.g., the second display channel media content)prior to changing to a third display channel. Another embodimentincludes retaining media content sourced from a higher priority displaychannel (e.g., a favorites channel). Alternatively, the user can bepresented at this point with a user interface screen (decision barkerscreen), as explained below, that provides the user with a choice ofbuffers to clear (and a choice of tuners to resource) to make room forthe third display channel media content.

FIG. 15 is a flow chart that illustrates example prioritizing stepsstarting from point B, which occurred after the threshold determinationof FIG. 13. Thus, if the buffering duration to both buffers met aminimum threshold, step 1516 comes into play to determine if the mediacontent of the first display channel and the second display channel wasbuffered into the respective buffers for an equal duration. If so, step1518 shows that a decision barker is provided to enable the user todecide which media content to displace (and consequently, which tuner toresource and which media content to retain). The decision barker will bedescribed in further detail below. Alternatively, other input variablescan be evaluated to provide a decision, for example retaining the mediacontent of a higher priority display channel (e.g., a favoriteschannel).

However, if the media content to both buffers was not buffered for anequal buffering duration, then the next step (step 1520) is to determinewhether the media content of the first display channel was buffered fora longer duration than the media content of the second display channel(i.e., relational input variables). It will be understood by those ofordinary skill in the art that the reference comparison can be reversed.For example, step 1520 can just as easily be described as determiningwhether the second display channel was buffered for a longer duration,or described as whether the media content of the second display channelwas buffered for a shorter duration, etc. If step 1520 results in anaffirmative determination, the prioritizing steps continue to point C(FIG. 16), otherwise the steps continue at point D (FIG. 17).

FIG. 16 is a flow chart that begins from point C, wherein step 1622compares the buffering duration of the first and the second displaychannel and determines whether the media content of the second displaychannel was buffered for a buffering duration at least equal to adefined percentage of the buffering duration of the media content of thefirst display channel. For instance, if the media content of the firstdisplay channel was buffered to the first buffer (TSB1 376, FIG. 4) fora duration of 30 minutes, a threshold percentage buffering duration,such as 50%, could be established, in one embodiment, at a user settingsmenu (not shown) at start-up, or configured at any other point whenusing the PVR mechanisms in other embodiments. By establishing athreshold percentage of, for example, 50%, if the media content of thesecond display channel was buffered into the second buffer (TSB2 378,FIG. 4) for 10 minutes, 10 minutes is less than 50% of 30 minutes, andthus the determination of step 1622 would lead to step 1624, whereintuner2 358 (FIG. 4) would be resourced for the third display channel andthe media content of the second display channel would be displaced bythe media content buffered from the third display channel.

However, continuing the example, if the media content of the seconddisplay channel was buffered for 25 minutes, this buffering durationexceeds the threshold percentage of 50%, and thus a decision barker canbe provided (step 1626) to enable the user to determine priority in thiscase. In one embodiment, the viewer configures when to allow thedecision barker to be displayed by entering input during a configurationsession. Furthermore, the viewer configures the percentage differencefrom the set threshold for when the decision barker is displayed.Alternatively, a decision barker is only presented to the viewer toenable the viewer to determine priority in cases deemed as a“close-case,” such as when near the percentage threshold. Alternatively,default threshold percentages can be provided in the software, or theuser can configure these threshold percentages in a user interfacescreen at start-up, or at other times, or additional input variables canbe evaluated.

FIG. 17 continues the prioritizing steps from point D, which resultedfrom the decision step 1520 in FIG. 15. In other words, the mediacontent of the first display channel was buffered for a shorter durationthan the media content of the second display channel. Step 1728 mirrorsthe decision step of step 1622 (FIG. 16), and determines whether themedia content of the first display channel was buffered for a bufferingduration at least equal to a defined percentage of the bufferingduration of the media content of the second display channel. If so, thedecision barker is displayed for user interaction (step 1730), otherwisethe first tuner (tuner1 354 FIG. 4) is resourced and the media contentof the first display channel is displaced (step 1732) to make room forthe media content of the third display channel (while retaining themedia content of the other buffer).

FIG. 18 is a screen diagram of an example decision barker screenprovided for by the PVR application 377 (FIG. 3B). The decision barkerscreen 1800 can be overlaid on a display of a media content instance, orpreferably, is a separate screen that contains a scaled down mediacontent display 1834. The decision barker screen 1800 further includesan instruction section 1836 that informs the user of the buffer spaceconflict, as well as directions as to how to resolve the conflict. Alist portion 1838 includes a select symbol 1893 and scroll arrow icons1894 and 1895 that suggest corresponding functionality to the selectbutton 393 and up and down arrows 394 and 395 of the remote controldevice 380 (FIG. 3D). The list portion 1838 preferably also includes alist of titles of the media content instances buffered for each displaychannel, as well as the times the instances were buffered as well as theduration of time each media content instance was buffered. The userscrolls to the display channel that the user wants to remove to makeroom for the third display channel. If the user decides that he or shewants to permanently record buffered content, he or she selects therecord options button “B”.

The PVR application 377 (FIG. 3B) of the present invention can beimplemented in hardware, software, firmware, or a combination thereof.In the preferred embodiment(s), the PVR application 377 is implementedin software or firmware that is stored in a memory and that is executedby a suitable instruction execution system. If implemented in hardware,as in an alternative embodiment, the PVR application 377 may beimplemented with any or a combination of the following technologies,which are all well known in the art: a discrete logic circuit(s) havinglogic gates for implementing logic functions upon data signals, anapplication specific integrated circuit (ASIC) having appropriatecombinational logic gates, a programmable gate array(s) (PGA), a fieldprogrammable gate array (FPGA), etc.

The PVR application 377 (FIG. 3B), which comprises an ordered listing ofexecutable instructions for implementing logical functions, can beembodied in any computer-readable medium for use by or in connectionwith an instruction execution system, apparatus, or device, such as acomputer-based system, processor-containing system, or other system thatcan fetch the instructions from the instruction execution system,apparatus, or device and execute the instructions. In the context ofthis document, a “computer-readable medium” can be any means that cancontain, store, communicate, propagate, or transport the program for useby or in connection with the instruction execution system, apparatus, ordevice. The computer readable medium can be, for example but not limitedto, an electronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, device, or propagation medium. Morespecific examples (a nonexhaustive list) of the computer-readable mediumwould include the following: an electrical connection (electronic)having one or more wires, a portable computer diskette (magnetic), arandom access memory (RAM) (electronic), a read-only memory (ROM)(electronic), an erasable programmable read-only memory (EPROM or Flashmemory) (electronic), an optical fiber (optical), and a portable compactdisc read-only memory (CDROM) (optical). Note that the computer-readablemedium could even be paper or another suitable medium upon which theprogram is printed, as the program can be electronically captured, viafor instance optical scanning of the paper or other medium, thencompiled, interpreted or otherwise processed in a suitable manner ifnecessary, and then stored in a computer memory.

It should be emphasized that the above-described embodiments of thepresent invention, particularly, any “preferred embodiments” are merelypossible examples of implementations, merely setting forth a clearunderstanding of the principles of the inventions. Many variations andmodifications may be made to the above-described embodiments of theinvention without departing substantially from the spirit of theprinciples of the invention. All such modifications and variations areintended to be included herein within the scope of the disclosure andpresent invention and protected by the following claims.

1. A method for receiving media content of multiple display channels ata digital home communication terminal (DHCT), comprising: receivingfirst media content corresponding to a first display channel at a firsttuner of the DHCT; receiving second media content corresponding to asecond display channel at a second tuner of the DHCT; and presenting toa user of the DHCT a plurality of options to receive third media contentusing one of the first and second tuners at a time overlapping at leastin part with a time in which the first and second media content arereceived.
 2. The method of claim 1, wherein receiving the first andsecond media content comprises receiving the first media content at afirst carrier frequency and receiving the second media content at asecond carrier frequency.
 3. The method of claim 1, wherein receivingthe first and second media content comprises receiving the first mediacontent corresponding to a first packet identifier (PID) and receivingthe second media content corresponding to a second PID.
 4. The method ofclaim 1, wherein receiving the first and second media content comprisesreceiving one or more signals carrying the first and second mediacontent.
 5. The method of claim 4, wherein the one or more signalscomprises an analog transmission signal.
 6. The method of claim 4,wherein the one or more signals comprises a digital transmission signal.7. The method of claim 1, further comprising buffering the first mediacontent into a first buffer space and buffering the second media contentinto a second buffer space.
 8. The method of claim 7, wherein the firstbuffer space and the second buffer space reside in separate storagedevices.
 9. The method of claim 7, wherein the first buffer space andthe second buffer space reside in a single storage device.
 10. Themethod of claim 9, wherein the single storage device comprises a harddisk drive.
 11. The method of claim 1, wherein presenting comprisesdisplaying a graphical user interface that provides the user an optionwhich, when selected, effectuates the reception of the third contentusing either the first or second tuner.
 12. The method of claim 1,wherein presenting comprises displaying a graphical user interface thatprovides the user an option which, when selected, effectuates which ofthe first media content or second media content to delete to receive thethird content.
 13. A digital home communication terminal (DHCT),comprising: a first tuner configured to receive first media contentcorresponding to a first display channel; a second tuner configured toreceive second media content corresponding to a second display channel;a memory with logic; and a processor configured with the logic to enablea user of the DHCT to effectuate reception by the DHCT of third mediacontent using one of the first and second tuners at a time overlappingat least in part with a time in which the first and second media contentare received.
 14. The DHCT of claim 13, wherein the first tuner isconfigured to receive the first media content at a first carrierfrequency, and wherein the second tuner is configured to receive thesecond media content at a second carrier frequency.
 15. The DHCT ofclaim 13, wherein the first tuner is configured to receive the firstmedia content corresponding to a first packet identifier (PID), andwherein the second tuner is configured to receive the second mediacontent corresponding to a second PID.
 16. The DHCT of claim 13, furthercomprising first and second buffers corresponding to the first andsecond tuners, respectively, the first buffer configured to receive thefirst media content, the second buffer configured to receive the secondmedia content.
 17. The DHCT of claim 16, wherein the first buffer andthe second buffer reside in one of separate storage devices and a singlestorage device.
 18. The DHCT of claim 13, wherein the processor isfurther configured with the logic to provide a video output signalcomprising information corresponding to a graphical user interface, thegraphical user interface configured to provide the user an option which,when selected, effectuates the reception of the third content usingeither the first or second tuner.
 19. The DHCT of claim 13, wherein theprocessor is further configured with the logic to provide a video outputsignal comprising information corresponding to a graphical userinterface, the graphical user interface configured to provide the useran option which, when selected, effectuates which of the first mediacontent or second media content to delete to receive the third content.20. A system, comprising: a digital home communication terminal (DHCT)residing in a subscriber television system (STS), the DHCT comprising: afirst tuner configured to receive first media content corresponding to afirst display channel; a second tuner configured to receive second mediacontent corresponding to a second display channel; a memory with logic;and a processor configured with the logic to provide a graphical userinterface (GUI) that enables a user of the DHCT to effectuate receptionby the DHCT of third media content using one of the first and secondtuners at a time overlapping at least in part with a time in which thefirst and second media content are received; and a television configuredto present the GUI, the GUI configured to provide the user an optionwhich, when selected, effectuates which of the first media content orsecond media content to delete to receive the third content.